Add support for suspending battery charging

The test is only expected to do anything on devices that support
the power.battery_input.suspended property.

Bug: 167636754
Test: atest FrameworksCoreTests:com.android.internal.os.BatteryInputSuspendTestPowerInputSuspendTest

Change-Id: I79e752be1ea370624c2b54d40ad0ec922dee69bc