Exit active mode on Escape key

Any key that outputs a Unicode character will allow the user to
exit the "active mode" that allows them to compose special
characters. However, pressing Escape doesn't do anything, as it
will not output any Unicode character.

This change adds an extra condition to exit active mode by pressing
the Escape key.

Bug: 271671045
Test: Flashed phone, confirmed that pressing Escape will cancel the
input of an accented character

Change-Id: Id3d04758c9fd4cdb65016cca3af30f611b7011e4