main/test.c: Add test to verify there were no registration errors.

This adds a test that will fail if any test failed to register. Also fail
if any test registration produced a warning about missing a leading or
trailing slash.

ASTERISK-25053 #close
Reported by: Corey Farrell

Change-Id: I93e50b8fcbcfa7f1f5b41b2c44a51685c09529c3