Add an API sample to show subtype enabler.

At least on AOSP InputMethodManager#showInputMethodAndSubtypeEnabler()
has been broken for long time.  Also, there has been a valid alternative
way to do the same thing.

This CL adds an API sample to officially encourage people to use
Settings.ACTION_INPUT_METHOD_SUBTYPE_SETTINGS intent rather than trying
to rely on InputMethodManager#showInputMethodAndSubtypeEnabler(), which
is highly likely to be broken.

Bug: 26189558
Change-Id: I915a2d81948598ed08b4ef9111bdd128fd93f3df
2 files changed