[url_launcher] docs: note about encoding URIs (flutter#2172)

Add a note about encoding URLs passed to the url_launcher in the packages README.

[path_provider] Updated documentation reflecting changes needed for t…

…esting (flutter#2815)

The recent federation of the Linux path provider might break tests, this updates the README.md to address those changes and direct the users how to mock the plugin in their tests.

[image_picker] fixes for iOS which doesn't present camera/albums with…

… more complex navigation (flutter#2755)

[image_picker] Add web support to the example app. (flutter#2816)

[image_picker_for_web] Remove android directory. (flutter#2817)

[image_picker_for_web] Introduce image_picker_for_web package (flutte…

…r#2802)

[path_provider] linux endorsement (flutter#2789)

Endorses path_provider_linux, manually registering its implementation as a workaround for flutter/flutter#52267

[path_provider] linux endorsement (flutter#2789)

Endorses path_provider_linux, manually registering its implementation as a workaround for flutter/flutter#52267

[path_provider] linux endorsement (flutter#2789)

Endorses path_provider_linux, manually registering its implementation as a workaround for flutter/flutter#52267

[path_provider] linux endorsement (flutter#2789)

Endorses path_provider_linux, manually registering its implementation as a workaround for flutter/flutter#52267