Add encodings option to the compression middleware

[wollomatic]

What does this PR do?

This adds an option to configure the allowed compression encodings to the compression middleware:

http:
  middlewares:
    test-compress:
      compress:
        encodings:
          - gzip
          - zstd
          - br

Implements #10927

Motivation

Some enterprise firewalls don't support zstd compression yet, so websites using Traefik 3.1 with the compress middleware can cause problems in some corporate networks.

More

• Added/updated tests
• Added/updated documentation

Additional Notes

Despite that enhancements should be merged into the master branch, I chose the v3.1 branch because the feature is only relevant for Traefik v3.1+

[kevinpollet]

Hi @wollomatic,

Thanks for this contribution,

I added a couple of comments and we rebased this pull request on branch v3.1 as this is a new feature.

[kevinpollet]

Hey @wollomatic,

We are reviewing your pull request, and we would like to iterate on it.
Is it ok for you if we push a review commit on it?

[wollomatic]

Hi @kevinpollet sure, thanks!

[kevinpollet]

Thanks 👍

[wollomatic]

Thank you!

[rtribotte]

Thanks!

[traefiker]

🚫 checks status: PR status: failure