[webview_flutter_platform_interface] Updates platform interface to new interface (#6846)

* Set new interface in main

* update pubspec changelog and readme

* exclude from all plugins app test

* delete all of platform interface

* add all back to platform interface

Author: bparrishMines

packages/webview_flutter/webview_flutter_platform_interface/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 2.0.0
+
+* **Breaking Change**: Releases new interface. See [documentation](https://pub.dev/documentation/webview_flutter_platform_interface/2.0.0/) and [design doc](https://flutter.dev/go/webview_flutter_4_interface)
+  for more details.
+* **Breaking Change**: Removes MethodChannel implementation of interface. All platform
+  implementations will now need to create their own by implementing `WebViewPlatform`.
+
 ## 1.9.5
 
 * Updates code for `no_leading_underscores_for_local_identifiers` lint.

packages/webview_flutter/webview_flutter_platform_interface/README.md

@@ -9,10 +9,10 @@ same interface.
 # Usage
 
 To implement a new platform-specific implementation of `webview_flutter`, extend
-[`WebviewPlatform`](lib/src/platform_interface/webview_platform.dart) with an implementation that performs the
+[`WebviewPlatform`](lib/src/webview_platform.dart) with an implementation that performs the
 platform-specific behavior, and when you register your plugin, set the default
 `WebviewPlatform` by calling
-`WebviewPlatform.setInstance(MyPlatformWebview())`.
+`WebviewPlatform.instance = MyPlatformWebview()`.
 
 # Note on breaking changes