Add tests for certificate import scenario

[kabicin]

Fixes #413

• Updates verify.sh to track image name instead of ID and to support modifiable images at runtime (i.e. cert generation).
• Add test-liberty-certificates project that generates dummy certificates in staging, then importing them into the Liberty image to emulate a BYO cert scenario.
• Update projects pointing to old image refs openliberty/open-liberty:kernel-slim-ubi