Added CMake option
OGS_DOWNLOAD_CPM_CACHE which downloads and uses the cpm cache.
Refactored CI pipeline for this:
- cpm cache job is run only on MR
- if there is a new cache, it automatically sets the corresponding entries in versions.json and commits to the MR (only for bilke/ogs atm).
- offline configure job only runs on master
Feature description was added to the changelog
Tests covering your feature were added?
Any new feature or behavior change was documented?