This removes all of the deprecated plugins from the tree, as well as all references to them.
They were being left in the tree only in case they needed critical fixes before the end of this year, when they will become completely unsupported and be officially discontinued on pub.dev. The end of the year is now close enough that such a release is extremely unlikely, and they are causing some maintenance burden (e.g., the tree is currently closed on an out-of-band failure in android_alarm_manager). In the event that we do have to push an emergency fix in the next several weeks, we can either temporarily restore the plugin from git history, or use a branch.
Minor related cleanup:
- Scanning the repository for remaining references turned up that `image_picker_for_web` and `video_player_for_web` had copypasta'd the package name of its example application from one of the deprecated plugins, so this fixes those names.
- Fixes `federation-safety-check` handling of top-level files in unfederated plugins that accidentally tripped federated plugin heuristics.
- Fixes `federation-safety-check` handling of deleted plugins, as it was crashing, and tests that.
- Fixes `make-deps-path-based` handling of deleted plugins, as it was crashing, and tests that.
The new safety check doesn't allow simple platform-interface-only
changes because it doesn't actually check that a non-interface package
is actually modified before failing it for a modified platform
interface.
This fixes that, and adds a test case covering it.
Creates a new command to validate that PRs don't change platform interface packages and implementations at the same time, to try to prevent ecosystem-breaking changes. See https://github.com/flutter/flutter/issues/89518 for context.
Per the explanation in the issue, this has carve-outs for:
- Changes to platform interfaces that aren't published (allowing for past uses cases such as making a substantive change to an implementation, and making minor adjustments to comments in the PI package based on those changes).
- Things that look like bulk changes (e.g., a mass change to account for a new lint rule)
Fixes https://github.com/flutter/flutter/issues/89518
