feat: アカウントをID/Name両方で取得できるように

[laminne]

close #785

What does this PR do?

• GET /accounts/:idをGET /accounts/:identifierに変更
  • IDまたはNameで取得できるように
• APIドキュメントの更新
• PrismaRepositoryの実装ミスで投稿を取得できない問題を修正
  • 同様の実装が数箇所あるはずなので別の箇所についてはIssueを立てて対処します

Additional information

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 76 lines in your changes missing coverage. Please review.

Project coverage is 49.17%. Comparing base (eca4510) to head (c344eb5).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/accounts/mod.ts	0.00%	26 Missing ⚠️
pkg/accounts/adaptor/controller/account.ts	0.00%	25 Missing ⚠️
pkg/accounts/router.ts	0.00%	16 Missing ⚠️
pkg/timeline/adaptor/repository/prisma.ts	0.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #794      +/-   ##
==========================================
- Coverage   49.41%   49.17%   -0.24%     
==========================================
  Files         149      149              
  Lines       13540    13614      +74     
  Branches     1051     1051              
==========================================
+ Hits         6691     6695       +4     
- Misses       6849     6919      +70     

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