[Telephony][Security Fix] Launch Browser only if device is unlocked.

Ignore the launch browser proactive cmd from modem to STK if the device screen is locked.

Bug: 404254549
Flag: EXEMPT Bugfix.
Test: Verified manually with TestApk
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:dcf5c112a93dc8fcc67d65434707e205fd79cee2)
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:928df99dd7389e24e953101766b0810e7e526555
Merged-In: I9f651c7f1c5674df5774f5a7609f6d3749b5c50c
Change-Id: I9f651c7f1c5674df5774f5a7609f6d3749b5c50c