H/QPackEncoder overloads accepting Encoding

[MihaZupan]

Adds overloads accepting an Encoding for header values to H/QPackEncoders.

This is a mirror of changes to H/QPackEncoder merged into runtime in dotnet/runtime#39468.

This is following the Shared code readme - if such changes are mirrored automagically, please close this PR.

Fixes #18943

[Tratcher]

if such changes are mirrored automagically, please close this PR.

For a change like this we want an explicit PR to make sure nothing breaks. Please ensure both PRs are merged on the same day so the automatic mirror tool doesn't run.

[MihaZupan]

The Runtime PR has been merged ~12h ago. I did run the aspnetcore build & tests listed in the readme before.

[Tratcher]

The Runtime PR has been merged ~12h ago. I did run the aspnetcore build & tests listed in the readme before.

Haha you missed the auto-mirror bot by about 15 minutes. I ran it manually just to confirm. #24449

[ghost]

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