flutter_tool: only enable wasm compile in master channel

flutter_tool: DRY up features that are fully enabled

Removes the beta-quality wording for Linux from messages in the tool.

Issue: https://github.com/flutter/flutter/issues/99697

Removes the beta-quality wording for macOS from messages in the tool.

Issue: https://github.com/flutter/flutter/issues/98680

This reverts commit 5fd259be.

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

Prep to make https://github.com/flutter/flutter/issues/73857 easier in the future.

This reverts commit ef474154.

Continued gradual rollout - dev is not that much riskier than master but will give much more data

This should be a mostly non breaking change for hot reload workflows that improves performance, but if you see anything odd with hot reload behavior on master please file a bug. This feature can also be disabled without any changes to the SDK with flutter config --no-single-widget-reload-optimization