[path_provider] Fix Android compatibility with 2.5 (flutter#4637)

PR flutter#4617 added a dependency on Dart auto-registration, but forgot to
bump the SDK requirement to 2.8 (where that feature was introduced for
Android). In order to fix older versions, this restores the previous
channel name so that the implementation here is compatible with the
default method channel registration used by Flutter 2.5 and earlier.

A follow-up will restore the package-specific channel name, but also
change the SDK requirement to >=2.8. This must be published first so
that the last published version that claims 2.5 compatibility actually
works with 2.5.

Fixes flutter/flutter#95706

[video_player] Update texture on seekTo (flutter#2758)

[path_provider] Switch Android to an internal method channel (flutter…

…#4617)

[video_player] Add 5.0 interface support (flutter#4627)

Allows the other video_player packages to use either 4.x or 5.x of
`video_player_platform_interface`, since the only breaking change
doesn't affect them (as it just removes test code that they no longer
use). This allows clients of `video_player` to no longer have a
transitive dependency on test packages, but doesn't create any version
lock with any unendorsed implementations that might exist.

Fixes flutter/flutter#83562

[video_player] Add 5.0 interface support (flutter#4627)

Allows the other video_player packages to use either 4.x or 5.x of
`video_player_platform_interface`, since the only breaking change
doesn't affect them (as it just removes test code that they no longer
use). This allows clients of `video_player` to no longer have a
transitive dependency on test packages, but doesn't create any version
lock with any unendorsed implementations that might exist.

Fixes flutter/flutter#83562

[video_player] Remove test code from platform interface (flutter#4589)

This is a breaking change to video_player_platform_interface to remove Pigeon mocks from the public interface. These should never have been there, as tests in packages outside of the platform interface should be mocking the platform interface rather than the method channel, but the app-facing tests weren't rewritten when they should have been so they ended up published to support the legacy tests. This creates an unwanted non-dev dependency on `flutter_test`, in addition to promoting an anti-pattern.

While making the breaking change, this also adopts `PlatformInterface`, removing `isMock` in favor of the standard mixin pattern provided by the base class.

Part of flutter/flutter#83562

[webview_flutter] Enable setAllowFileAccess on Android setting when l…

…oading files (flutter#4601)

Prevent setting user agent string to default value on every rebuild (f…

…lutter#4618)

[video_player] Eliminate platform channel from mock platform (flutter…

…#4588)

[local_auth] Switch to new analysis options (flutter#4604)

Removes the legacy analysis options and fixes all violations. Most fixes were automated `dart fix --apply` changes.

Part of flutter/flutter#76229