[wiki migration] Ecosystem team pages (#148589)

This puts the wiki pages owned by the Ecosystem team into the docs/ecosystem directory as planned in [flutter.dev/go/migrate-flutter-wiki-spreadsheet](https://docs.google.com/spreadsheets/d/1x65189ZBdNiLRygpUYoU08pwvXD4M-Z157c6pm8deGI/edit?usp=sharing) 

It also adds the ecosystem team labels to the label bot for future PRs.

Changes to the content were only updating cross links. The remaining wiki links will be updated after the rest of the pages are relocated, the original wiki links still work in the meantime.

Part of https://github.com/flutter/flutter/issues/145009

.github/labeler.yml

@@ -116,6 +116,11 @@ framework:
     - any-glob-to-any-file:
       - packages/integration_test/**/*
 
+package:
+  - changed-files:
+    - any-glob-to-any-file:
+      - docs/ecosystem/**/*
+
 platform-ios:
   - changed-files:
     - any-glob-to-any-file:
@@ -138,6 +143,11 @@ platform-web:
       - '**/*.expect'
       - '**/*test_fixes*'
 
+team-ecosystem:
+  - changed-files:
+    - any-glob-to-any-file:
+      - docs/ecosystem/**/*
+
 tool:
   - changed-files:
     - any-glob-to-any-file: