Prepare for using azure cleanroom in tests

[DomAyre]

Motivation

When attempting to add azure cleanroom support, I noticed that the KMS code defines a "workspace" which is assumed to have the same structure as the workspace created when running sandbox.sh from ghcr.io/microsoft/ccf/app/dev/${CCF_PLATFORM}:${TAG}.

Since the network created by azure cleanroom doesn't have this structure we need to update the code that has this assumption.

Changes

• [x] Simplify the devcontainer
• [x] Have self contained script directories for different backends
  • up.sh script sets env variables such as KMS_URL which are specific to type of backend
• [x] Don't assume anything about CCF workspace to enable using Azure Cleanroom
  • In practice this means setting full paths to things like member and service certs instead of setting a workspace and assuming the structure
• [x] Added scripts for calling each endpoint
  • Makes local testing much easier
• [x] Update makefile targets to use this new code

[beejones]

we are missing tests for keyunwrap

[DomAyre]

we are missing tests for keyunwrap

I agree, that isn't for this PR to address, see the original PR which added these tests. (There's a few tests which weren't completed and I deferred for future PRs because I had to work on other things)

I need to prioritise working on the self hosting of CCF over the KMS's test coverage, but it would be great if you could add the missing tests in a future PR

[DomAyre]

Putting back into draft state while I fix some non-trivial merge conflicts with the settingsPolicy PR

[DomAyre]

Merge conflicts are done, back to "ready to review"