feat: added facets (#247)

[myConsciousness]

1. Description

1.1. Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have read the Contributor Guide and followed the process outlined for submitting PRs.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples.

1.2. Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

1.3. Related Issues

[codecov-commenter]

Codecov Report

Merging #247 (28afe43) into main (5a2e0d3) will decrease coverage by 0.42%.
The diff coverage is 0.00%.

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@@            Coverage Diff             @@
##             main     #247      +/-   ##
==========================================
- Coverage   78.49%   78.07%   -0.42%     
==========================================
  Files         100      101       +1     
  Lines         744      748       +4     
==========================================
  Hits          584      584              
- Misses        160      164       +4     

Impacted Files	Coverage Δ
packages/bluesky/lib/src/entities/facet_link.dart	100.00% <ø> (ø)
...ckages/bluesky/lib/src/entities/facet_mention.dart	100.00% <ø> (ø)
packages/bluesky/lib/src/entities/reply_ref.dart	0.00% <0.00%> (ø)
packages/bluesky/lib/src/feeds/feeds_service.dart	95.00% <0.00%> (-5.00%)	⬇️

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