Move SPECIAL_FUNCTION from .kcm to .idc files

Currently, the only use of device-specific .kcm files is to specify
SPECIAL_FUNCTION flag (meaning that this keyboard is only used to
perform system control functions and not for typing).

Instead of adding a special .kcm file, use .idc files with se
keyboard.specialFunction = 1 to achieve the same functionality. This
allows the removal of all device-specific .kcm files.

The .kcm functionality will remain in P (with a warning). The
functionality will be removed in Q.

Bug: 67718661
Test: tested the codepath on Android wear device via logging
Change-Id: I1b4572456fa42caae1282dd8d3557820671b3610