Language detection fixes.

- Load foreign language detection score threshold from model
- Pass resource config language to native code instead of Locale.getDefault()
- Avoid nullpointer exception in ExtrasUtils
- Don't set action_intents extras if empty

Bug: 124791964
Bug: 124794807
Test: atest core/tests/coretests/src/android/view/textclassifier
Change-Id: I2593d7cb4d364d8bf26239ed59b7212f79ddc350