Use /to tooling links for pub redirects (#6279)

In an effort to standardize on `/to` for tooling redirects.

firebase.json

@@ -366,9 +366,21 @@
       { "source": "/support{,/**}", "destination": "/community", "type": 301 },
 
       { "source": "/to/doc-comment-references", "destination": "/tools/doc-comments/references", "type": 301 },
+      { "source": "/to/downgrade-testing", "destination": "/tools/pub/dependencies#test-with-downgraded-dependencies", "type": 301 },
       { "source": "/to/enforce-lockfile", "destination": "/tools/pub/packages#get-dependencies-for-production", "type": 301 },
       { "source": "/to/main-function", "destination": "/language/functions#main", "type": 301 },
+      { "source": "/to/package-discontinue", "destination": "/tools/pub/publishing#discontinue", "type": 301 },
+      { "source": "/to/package-retraction", "destination": "/tools/pub/publishing#retract", "type": 301 },
+      { "source": "/to/pub-cache", "destination": "/tools/pub/cmd/pub-cache", "type": 301 },
+      { "source": "/to/pub-content-hashes", "destination": "/tools/pub/glossary#content-hashes", "type": 301 },
+      { "source": "/to/pub-false-secrets", "destination": "/tools/pub/pubspec#false_secrets", "type": 301 },
+      { "source": "/to/pub-ignore", "destination": "/tools/pub/publishing#what-files-are-published", "type": 301 },
+      { "source": "/to/pub-security-advisories", "destination": "/tools/pub/security-advisories", "type": 301 },
       { "source": "/to/pub-workspaces", "destination": "/tools/pub/workspaces", "type": 301 },
+      { "source": "/to/publish-from-github", "destination": "/tools/pub/automated-publishing#publishing-packages-using-github-actions", "type": 301 },
+      { "source": "/to/publish-with-service-account", "destination": "/tools/pub/automated-publishing#publishing-from-google-cloud-build", "type": 301 },
+      { "source": "/to/sdk-constraint", "destination": "/tools/pub/pubspec#sdk-constraints", "type": 301 },
+      { "source": "/to/sdk-version-pinning", "destination": "https://github.com/dart-lang/sdk/blob/main/docs/Flutter-Pinned-Packages.md", "type": 301 },
       { "source": "/to/web-debug-extension", "destination": "https://chromewebstore.google.com/detail/dart-debug-extension/eljbmlghnomdjgdjmbdekegdkbabckhm", "type": 301 },
 
       { "source": "/tools/**/download{,.html,/**}", "destination": "/get-dart", "type": 301 },