Prevent InputMethodManager call into DelegateImpl (1/N)

InputMethodManager#DelegateImpl is a delegation for
ImeFocusController to call into InputMethodManager.

Ideally IMM don't need to rely on DelegateImpl. Move
the IMM#hasActiveInputConnection implemetation from
DelegateImpl to make consistency.

Bug: 243778447
Bug: 182259171
Test: atest CtsInputMethodTestCases
Change-Id: I4246fd077b8ddf741311defb7a1b9175136bb769