nfc(api): Address API council feedback for setReaderMode

1. Document the difference with the existing enableReaderMode() API.
2. Rename to setReaderModePollingEnabled.

Bug: 321949865
Test: atest NfcAdapterTest
Change-Id: Ifbabeb6e988e0b4d77bf18a1f0ba531b186a9a6a
3 files changed