Use permission to limit the app to use app's autofill

Based on the feedback from 1p app, to limit the usage of the new Client
Suggestions API so that apps don't degrade the current autofill
experience. And introduce a permission that will be automatically
granted to the browser role. So browsers can hold this permission to
have an AutofillRequestCallback.

Bug: 272398880
Test: atest PermissionPolicyTest#platformPermissionPolicyIsUnaltered
      atest android.autofillservice.cts.client.ClientSuggestionsInlineTest
      atest android.autofillservice.cts.client.ClientSuggestionsTest
Change-Id: I32b58ca24d3e73735591fb6409ce34106896df4f