Control API review changes

* Add documentation to Device types
* Replace singletons in ControlAction and ControlTemplate to getter
static functions.
* Add javadoc for MODES and FLAG_MODE in TemperatureControlTemplate.
* Removed ThumbnailTemplate instead of updated javadocs. Determined
not necessary anymore
* Remove MultiFloatAction - no longer needed
* Removed reliant sysui code

Bug: 150630500
Test: atest ControlTemplateTest ControlActionTest
Change-Id: Ic4f60c789ce959205137944380e78622d76581a4