enhance: 連合モードにあわせてフロントエンドを変化させるように

[kakkokari-gtyih]

What

• metaに連合モードを公開するように
• 連合モードに応じてフロントエンドを対応させるように（詳細はコミットメッセージを参照のこと）

Why

Fix #15111

Additional info (optional)

• アカウントの移行に関してはAPIレベルでの制限が別途必要な可能性があるため一旦保留→ 連合が無効化されていてもアカウントの移行操作ができる（かも） #15113
• GTLはAPIレベルでの制限（or ベースポリシーを変えてもらって運用でカバー？）が必要なので保留

Checklist

• Read the contribution guide
• Test working in a local environment
• (If needed) Add story of storybook
• (If needed) Update CHANGELOG.md
• (If possible) Add tests

[codecov]

Codecov Report

Attention: Patch coverage is 4.37956% with 131 lines in your changes missing coverage. Please review.

Project coverage is 41.64%. Comparing base (dac3b1f) to head (1af944c).
Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
packages/frontend/src/pages/about.vue	0.00%	30 Missing ⚠️
packages/frontend/src/components/MkWidgets.vue	0.00%	15 Missing ⚠️
packages/frontend/src/pages/search.note.vue	0.00%	12 Missing ⚠️
packages/frontend/src/ui/_common_/common.ts	0.00%	12 Missing ⚠️
...ckages/frontend/src/components/MkInstanceStats.vue	0.00%	11 Missing ⚠️
packages/frontend/src/scripts/please-login.ts	10.00%	9 Missing ⚠️
packages/frontend/src/widgets/index.ts	0.00%	8 Missing ⚠️
...ges/frontend/src/components/MkUserSelectDialog.vue	0.00%	7 Missing ⚠️
packages/frontend/src/pages/settings/privacy.vue	0.00%	5 Missing ⚠️
...s/frontend/src/components/MkSignupDialog.rules.vue	0.00%	4 Missing ⚠️
... and 8 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #15112      +/-   ##
===========================================
+ Coverage    38.91%   41.64%   +2.72%     
===========================================
  Files         1563     1567       +4     
  Lines       197745   203600    +5855     
  Branches      3330     3704     +374     
===========================================
+ Hits         76960    84784    +7824     
+ Misses      120174   118211    -1963     
+ Partials       611      605       -6     

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[github-actions]

このPRによるapi.jsonの差分

差分はこちら

--- base
+++ head
@@ -82440,6 +82440,14 @@
           },
           "maxFileSize": {
             "type": "number"
+          },
+          "federation": {
+            "type": "string",
+            "enum": [
+              "all",
+              "specified",
+              "none"
+            ]
           }
         },
         "required": [
@@ -82493,7 +82501,8 @@
           "themeColor",
           "policies",
           "noteSearchableScope",
-          "maxFileSize"
+          "maxFileSize",
+          "federation"
         ]
       },
       "MetaDetailedOnly": {

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