Send `Accept` header to universal resolver

[jasny]

Issue

According to the latest draft of the DID Resolution standard (v0.3); if the value of the Accept HTTP header is absent, the HTTP response body should be the DID document and not the DID resolution.

To get the DID resolution as response, you should send the header

Accept: application/ld+json;profile="https://w3id.org/did-resolution"

See https://w3c-ccg.github.io/did-resolution/#bindings-https

Universal Resolver does not follow this part of the standard and returns a DID resolution if the Accept header is omitted. To get a DID document, you must send the header

Accept: application/did+ld+json

Solution

By explicitly sending the Accept header, the UniversalResolver plugin can also be used for other services (like ours) that implement DID Resolution v0.3.

What is being changed

An Accept header is added with the value application/ld+json;profile="https://w3id.org/did-resolution" when doing the HTTP request in resolve.

Quality

Check all that apply:

• [X] I want these changes to be integrated
• [X] I successfully ran pnpm i, pnpm build, pnpm test, pnpm test:browser locally.
• [x] I allow my PR to be updated by the reviewers (to speed up the review process).
• [ ] I added unit tests.
• [ ] I added integration tests.
• [X] I did not add automated tests because there are no existing tests for this class, and I am aware that a PR without tests will likely get rejected.

Details

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: -0.01 :warning:

Comparison is base (6981e68) 84.48% compared to head (f8ce4e5) 84.48%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## next #1203 +/- ## ========================================== - Coverage 84.48% 84.48% -0.01% ========================================== Files 158 158 Lines 16625 16626 +1 Branches 1823 1823 ========================================== Hits 14046 14046 - Misses 2579 2580 +1 ``` | [Impacted Files](https://app.codecov.io/gh/uport-project/veramo/pull/1203?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uport-project) | Coverage Δ | | |---|---|---| | [packages/did-resolver/src/universal-resolver.ts](https://app.codecov.io/gh/uport-project/veramo/pull/1203?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uport-project#diff-cGFja2FnZXMvZGlkLXJlc29sdmVyL3NyYy91bml2ZXJzYWwtcmVzb2x2ZXIudHM=) | `84.88% <0.00%> (-1.00%)` | :arrow_down: |

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