[url_launcher] Add a new launchUrl to platform interface (flutter#5966)

This creates a new platform interface method for launching that closely
parallels the new public-facing API, so that implementations can switch
to implementing a more platform-neutral implementation. This will pave
the way for things like cleanly implementing
`externalNonBrowserApplication` support on non-iOS platforms.

A follow-up will switch the app-facing package to call this new methods
instead of the legacy method.

Implementation packages can adopt the new method as is useful for them;
eventually we can do a cleanup pass if we want to fully deprecate the
old method.

Added ignore deprecation comments to `styleFrom` button APIs (cont) (f…

…lutter#5983)

Added ignore deprecation comments to `styleFrom` button APIs (cont) (f…

…lutter#5983)

[video_player] Fix disposed VideoPlayerController throwing an error w…

…hen calling dispose() again (flutter#5952)

[path_provider]: Migrated path_provider for android to pigeon. (flutt…

…er#5959)

[image_picker] Switch Android to internal method channel (flutter#5958)

[google_maps_flutter] Switch web to structured options (flutter#5965)

[url_launcher] Fixes call to setState after dispose. (flutter#5963)

Ignore deprecation for `styleFrom` button APIs (flutter#5945)

Ignore deprecation for `styleFrom` button APIs (flutter#5945)