Fix non-unique PendingIntent issue with TCImpl.

As per the referenced bug, we're running into issues where apps are
being fired with stale intents. The reason is because we need intents we
fire to be unique by Intent.filterEquals. Some of the intents we
generate put unique data in the intent extra which is not considered by
filterEquals. The solution here is to create PendingIntents with unique
request codes (using classifiedText.hashCode()).
See more info about this in
https://developer.android.com/reference/android/app/PendingIntent.html

Bug: 77930684
Test: manually tested broken scenarios. See referenced bug
Test: bit FrameworksCoreTests:android.view.textclassifier.TextClassificationManagerTest
Test: bit CtsViewTestCases:android.view.textclassifier.cts.TextClassificationManagerTest
Test: bit FrameworksCoreTests:android.view.textclassifier.TextClassificationTest
Test: bit CtsWidgetTestCases:android.widget.cts.TextViewTest
Test: bit FrameworksCoreTests:android.widget.TextViewActivityTest
Change-Id: Ib7275f94ca5ada51e4ba191742d4b614df12e1ea