Add auto PiP on Android and redesign stream overlay (#218)

* Improve PiP behavior (Android)
Added the ability to enter PiP mode when leaving the app on Android.

* Add automatic PiP option

* Redesign video overlay

* Update stream card uptime counter

* Use gradient for overlay opacity

* Restore play button when paused on iOS

* Restore refresh button on overlay

* Prefer above for category tooltip

* Increase default overlay opacity to 80%

* Improve pip behavior

* Fix uptime setState after dispose

* Remove automatic pip option
Redundant since you can disable it in system settings

* Check if `setAutoEnterEnabled` is available

* Fix missing pip auto enter

* Disable auto pip when leaving channel

* Fix pip exception on iOS

pubspec.lock

@@ -281,13 +281,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.0.1"
-  floating:
-    dependency: "direct main"
-    description:
-      name: floating
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.1.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -861,6 +854,15 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.0.2"
+  simple_pip_mode:
+    dependency: "direct main"
+    description:
+      path: "."
+      ref: HEAD
+      resolved-ref: "1acaf4fc25cc87dbc5ce07f341ad4fd2ff086f4f"
+      url: "https://github.com/tommyxchow/simple_pip_mode_flutter"
+    source: git
+    version: "0.8.0"
   sky_engine:
     dependency: transitive
     description: flutter