Power: Add a flag and internal API for disabling wakelocks

Add a flag in PowerManagerService and when it's true, all partial
wakelocks will be disabled. Otherwise wakelocks will follow
original rule for disable/enable.

Also add an API to internal service to change the value of this
flag.

Bug: 370557028
Test: atest PowerServiceTests
Flag: com.android.server.power.feature.flags.force_disable_wakelocks
Change-Id: Ibb278f48654e00f90be7b744dc7107accfe879e1