[camera][draft] Add camera plugin (#29)

Added the first draft version, but there are still a lot of unimplemented features.

packages/camera/example/pubspec.yaml

@@ -0,0 +1,32 @@
+name: camera_example
+description: Demonstrates how to use the camera plugin.
+publish_to: none
+
+environment:
+  sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=1.22.0"
+
+dependencies:
+  camera: ^0.8.1+7
+  camera_elinux:
+    path: ../
+  flutter:
+    sdk: flutter
+  path_provider: ^2.0.0
+  path_provider_elinux:
+    path: ../../path_provider
+  video_player: ^2.1.4
+  video_player_elinux:
+    path: ../../video_player
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  flutter_driver:
+    sdk: flutter
+  integration_test:
+    sdk: flutter
+  pedantic: ^1.10.0
+
+flutter:
+  uses-material-design: true