Apply labelers and handle language for PWI home

[estrattonbailey]

Noticed two things were happening:

1. PWI wasn't applying mod authorities to getFeed requests
2. PWI language selector wasn't applying to getFeed requests

I don't think we've ever noticed the first, and the second I broke when I untangled appLanguage from contentLanguages in #5384. We used to set contentLanguages to match the appLanguage when that field was changed. I understood this to be a UX decision without realizing that it was load bearing for the PWI experience. Since post record lang field doesn't support regional codes either, I don't think this has ever worked as intended for "app" languages with region codes.

This PR borrows the labeler logic from our base Agent class, and pulls the language value we pass to getFeed from the appLanguage setting, stripping out a region code if it exists.

Testing

• check that atproto-accept-labelers is applied for PWI feed fetches
  • you can check atproto-content-labelers to see which are applied
• switch languages to our large market languages and make sure there's different content

[github-actions]

Old size	New size	Diff
7.9 MB	7.9 MB	149 B (0.00%)

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