PMS: Add shell command to toggle FIXED_PERFORMANCE

Adds a shell command to toggle FIXED_PERFORMANCE mode if the AIDL
version of the Power HAL is available:

  cmd power set-fixed-performance-mode-enabled [true|false]

Bug: 152342542
Bug: 22408132
Test: Manual, observe with ALOG that call makes it to PMS JNI
Change-Id: Id0106c87f3ab3dcef8e81553d4ebc93cd0b2c56f