ActivityManager: add API for wifi bug report

Under certain (limited) conditions, we would like to
automatically trigger a bug report to help diagnose
Wifi problems.

The regular bugreport can't be used for this purpose,
as it takes a long time to generate. To support
lightweight auto-bug generation, add a Wifi-specific
bugreport.

Bug: 69934148
Test: manual

Manual test
-----------
- boot walleye
- enable wifi
- connect to googleguest
$ adb root
$ adb shell pkill -f 'wifi@'
- notice "Bug report #1 captured" notification
$ adb pull '/data/user_de/0/com.android.shell/files/bugreports
$ unzip bugreports/*.zip
$ grep "was the duration of 'DUMPSTATE'" bugreport*.txt
->  ------ 1.548s was the duration of 'DUMPSTATE' ------

Change-Id: If657eb8f61b16cefe717c977663438c28f515bd7