Remove ImfLock dependency from IMM#get*InputMethod()

With this CL the following APIs and internal APIs stop acquiring
ImfLock.

 * InputMethodManager#getCurrentInputMethodInfo()
 * InputMethodManager#getCurrentInputMethodInfoAsUser()
 * InputMethodManager#getInputMethodList()
 * InputMethodManager#getInputMethodListAsUser()
 * InputMethodManager#getEnabledInputMethodList()
 * InputMethodManager#getEnabledInputMethodListAsUser()
 * InputMethodManager#getEnabledInputMethodSubtypeList()
 * InputMethodManager#getEnabledInputMethodSubtypeListAsUser()
 * InputMethodManagerInternal#getInputMethodListAsUser()
 * InputMethodManagerInternal#getEnabledInputMethodListAsUser()
 * InputMethodManagerInternal#getEnabledInputMethodSubtypeListAsUser()

Other than such performance implications, API behaviors remain
unchanged.

Fix: 354323416
Test: presubmit
Flag: EXEMPT refactor
Change-Id: Ie01cf0d20bd2901ca642acd85825082ac2027933