Add oppressive language presubmit

BUG=b:162024466
TEST=try to upload a CL with a blocked term

Change-Id: Icf078ecbd1c11aef7df664248cb9f2058912d3ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/inputcontrol/+/2575498
Tested-by: Harry Cutts <hcutts@chromium.org>
Auto-Submit: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: Sean O'Brien <seobrien@chromium.org>