Formalize capitalization

Author: helin24

src/io/flutter/FlutterBundle.properties

@@ -189,8 +189,8 @@ icon.preview.disallow.package.title=Unsupported icon package
 icon.preview.analysis=Checking icons...
 
 widget.preview.initializing=Initializing Flutter Widget Preview...
-widget.preview.starting=Starting Flutter widget preview web server...
-widget.preview.loading=Loading widget preview at {0}...
+widget.preview.starting=Starting Flutter Widget Preview web server...
+widget.preview.loading=Loading Flutter Widget Preview at {0}...
 widget.preview.error=Error: {0}
-widget.preview.sdk.too.old=Flutter SDK version is too old for widget preview. Please update your SDK.
+widget.preview.sdk.too.old=Flutter SDK version is too old for Flutter Widget Preview. Please update your SDK.
 flutter.sdk.not.found=Flutter SDK not found.