Publish web_embedding (#1777)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

<!-- Links -->
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[CLA]: https://cla.developers.google.com/
[Discord]: https://github.com/flutter/flutter/wiki/Chat
[Contributors Guide]:
https://github.com/flutter/samples/blob/main/CONTRIBUTING.md


Co-authored-by: Mark Thompson
<2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: David Iglesias <ditman@gmail.com>

Co-authored-by: Mark Thompson <2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: David Iglesias <ditman@gmail.com>

web_embedding/ng-flutter/flutter/.metadata

@@ -0,0 +1,45 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled.
+
+version:
+  revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+  channel: master
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+    - platform: android
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+    - platform: ios
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+    - platform: linux
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+    - platform: macos
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+    - platform: web
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+    - platform: windows
+      create_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+      base_revision: f41ae4f4c925336400b11dc02986c1b4d78a173c
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'