[omnibox] Add exhaustive unit test for Pedal concept matching

This CL adds a unit test to check possible interactions between
synonym groups and Pedals for all existing implementations. The
test documents and ensures that exactly one Pedal is triggered
for each literal expression, regardless of synonym order.

Bug: 893183
Change-Id: I35e93e7511a504c260d498186b04d0a81bf3d804
Reviewed-on: https://chromium-review.googlesource.com/c/1416973
Commit-Queue: Orin Jaworski <orinj@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623925}
2 files changed