[CMAKE] Rename the test wrapper util

Summary:
The test_wrapper.sh is currently used to run the unit tests, but is not
limited to this. This is in fact a generic wrapper for any runnable,
which silence the output unless it fails.
This diff renames the script to better reflect its intent.

Test Plan:

ninja check

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D7469