TextClassifier: Ensure url scheme is in lowercase

 packageManager.resolveActivity(intentWithUppercaseScheme, 0) returns null.
 This means we don't find an activity to handle the browser intent.
 Create a browser intent with url's scheme in lowercase instead.

Test: bit FrameworksCoreTests:android.view.textclassifier.TextClassificationManagerTest
Fixes: 36504599
Change-Id: Idb0c5b73d54cf77d5d6fb4ee0af4478ec11e8b82