Convert validate_framework_keymaps to Android.bp

The primary purpose of validate_framework_keymaps is to perform checks
on all *.kl, *.kcm, and *.idc files using the "validatekeymaps -q"
command. This action can be replaced by using a genrule.

Bug: 318785074
Test: m validate_framework_keymaps
Change-Id: I657466d7ee2cec29900beeb0610cb0d30f34f92e