Add details to the BAL allow record

When evaluating a Background Activity launch the allow_reason is right now a combination of many different factors. The goal of this change is to make this more transparent and especially record the opt-in status (of the app) to allow BAL.

LOG_STORAGE_INCREASE(GB/week): 1
TMPLOG_STORAGE_INCREASE(GB): 1
DATAPOL_SUGGESTIONS_ACKNOWLEDGED=TRUE

Bug: 315545426
Test: atest BackgroundActivityLaunchTest
Change-Id: If8374a8cb03591ebbb99c0b2e60e2cd9ec1e770d