Add HAL method to return SupportInfo object for PowerHAL

Add a way for the PowerHAL to return a single official, canonical
support object for all of the things it does or doesn't support,
alleviating the need for continued plumbing here by consolidating
all of the info into one place.

Test: atest VtsHalPowerTargetTest
Bug: 367803904
Flag: EXEMPT HAL interface change
Change-Id: I567a44ccc84575779ad3083f82ea5483ef1fb907