Prevent launchedFromPackage spoofing via FLAG_ACTIVITY_FORWARD_RESULT.

Bug: 457742426
Test: atest ActivityStarterTests
Test: Verified via test app
Flag: EXEMPT CVE_FIX
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:3bb240273822e41f3c6911c60d15983a600308f7
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:79fe04dbdf31ab80311069a4d0a7b518d47c31ac
Merged-In: Ic9637c56803b00acc9fca59f8092ed02dd46a4fb
Change-Id: Ic9637c56803b00acc9fca59f8092ed02dd46a4fb
2 files changed