enhance(client): show Unicode emoji tooltip with its name

[saschanaz]

What

1. MkReactionViewer and MkEmoji now shows the tooltip with the name when including Unicode emoji, lazily computed on pointerenter
2. Some TypeScript related refactoring

Why

1. Searching from an array with 2000 items for every emoji felt like too energy-consuming, so I decided to do it lazily on pointerenter. (But I have no actual performance profile 🤔)

• altはOSで各言語に読めるようになるので変更不要 / alt is not changed here as OSes should be able to read it in each language.

3. For less warnings

Additional info (optional)

[codecov]

Codecov Report

Merging #9399 (6bf1e0f) into develop (1b6473a) will decrease coverage by 0.00%.
The diff coverage is n/a.

❗ Current head 6bf1e0f differs from pull request most recent head fcca335. Consider uploading reports for the commit fcca335 to get more accurate results

@@             Coverage Diff             @@
##           develop    #9399      +/-   ##
===========================================
- Coverage    22.42%   22.42%   -0.01%     
===========================================
  Files          702      702              
  Lines        65774    65777       +3     
  Branches      2127     2127              
===========================================
  Hits         14748    14748              
- Misses       51026    51029       +3     

Impacted Files	Coverage Δ
...kages/backend/src/server/WellKnownServerService.ts	0.00% <0.00%> (ø)

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[syuilo]

• altを削除すると、テキストをコピーしたときに絵文字が消えます

• Searching from an array with 2000 items for every emoji felt like too energy-consuming

  • これはコード内にコメントとして残しておくと良いと思います。