HTTP routes to serve files with correct content type and etag headers

[adzialocha]

This PR switches from using symlinks and the ServeDir struct from tower to HTTP routes which resolve the blobs manually and respond with the correct content types.

Notable changes:

• Files are now directly stored into the /blobs folder, without sub-directories using their document view id
• HTTP requests to /blobs/:documentId respond with the latest blob
• HTTP requests to /blobs/:documentId/:viewId respond with the blob at that view id (this makes /blobs/documents/... obsolete
• Responses contain Content-Type header set by the blob's self-declared MIME type
• Responses contain ETag header
• Requests with a If-None-Match header might be responded with a 304 "Not Modified" in case the entity tags matched
• Added update_blob test method
• Changed add_blob test method to slice up blob data into "pieces" by given "max piece length" variable
• Renamed test client method to reflect that it is not anymore for GraphQL only
• Changed all fs methods to async tokio::fs

Closes #541 and #501

📋 Checklist

• [x] Add tests that cover your changes
• [x] Add this PR to the Unreleased section in CHANGELOG.md
• [x] Link this PR to any issues it closes
• [x] New files contain a SPDX license header

[adzialocha]

Observing some weird race-conditions (locally and in CI) where files do not exist yet when running fs methods. After changing this to tokio::fs (making it async) it became more stable .. I'm not exactly sure but tokio seems to bring different guarantees with its methods.

By the way, this is an interesting method I've stumbled upon: https://docs.rs/tokio/latest/tokio/fs/struct.File.html#method.sync_data - don't think we need it (we're fine with the OS managing files however it wants, as long as we can read from them), just good to keep in mind that file systems are weird.

[codecov[bot]]

Codecov Report

Patch coverage: 93.84% and project coverage change: +0.08% :tada:

Comparison is base (6c5d477) 92.42% compared to head (edc0b30) 92.50%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #544 +/- ## =============================================== + Coverage 92.42% 92.50% +0.08% =============================================== Files 105 105 Lines 17663 17932 +269 =============================================== + Hits 16325 16588 +263 - Misses 1338 1344 +6 ``` | [Files Changed](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda) | Coverage Δ | | |---|---|---| | [aquadoggo/src/config.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9jb25maWcucnM=) | `81.25% <ø> (ø)` | | | [aquadoggo/src/materializer/tasks/blob.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9tYXRlcmlhbGl6ZXIvdGFza3MvYmxvYi5ycw==) | `53.33% <52.17%> (-22.55%)` | :arrow_down: | | [aquadoggo/src/http/api.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9odHRwL2FwaS5ycw==) | `92.70% <93.58%> (+26.03%)` | :arrow_up: | | [aquadoggo/src/db/stores/blob.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9kYi9zdG9yZXMvYmxvYi5ycw==) | `97.38% <100.00%> (ø)` | | | [aquadoggo/src/graphql/mutations/publish.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL211dGF0aW9ucy9wdWJsaXNoLnJz) | `98.71% <100.00%> (+0.03%)` | :arrow_up: | | [aquadoggo/src/graphql/queries/collection.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL3F1ZXJpZXMvY29sbGVjdGlvbi5ycw==) | `99.60% <100.00%> (ø)` | | | [aquadoggo/src/graphql/queries/document.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL3F1ZXJpZXMvZG9jdW1lbnQucnM=) | `99.06% <100.00%> (ø)` | | | [aquadoggo/src/graphql/queries/next\_args.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL3F1ZXJpZXMvbmV4dF9hcmdzLnJz) | `97.00% <100.00%> (ø)` | | | [aquadoggo/src/graphql/schema.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL3NjaGVtYS5ycw==) | `92.79% <100.00%> (ø)` | | | [aquadoggo/src/graphql/tests.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL3Rlc3RzLnJz) | `100.00% <100.00%> (ø)` | | | ... and [7 more](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda) | | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/p2panda/aquadoggo/pull/544/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda)

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