Merge ControlledInputConnectionWrapper into parent class

Since ControlledInputConnectionWrapper is the only derived class
of IInputConnectionWrapper hence it doesn't have a reason keep them
separate.

Bug: 167948374
Bug: 163450598
Test: atest CtsInputMethodTestCases
Change-Id: Ice1ea23dcb2351b56ef03b507d8aec8f8fb7b30a