Draft: build: simplify the CMake code that calculates versions

The CMake code that was calculating versions was quiet complicated: it depended on if the code was run in GitLab CI or not, if a Git tag was defined or not, and if not tag was defined, on the current Git branch.

This commit simplifies this logic:

• The caller of CMake can now provide the variables ASAPO_VERSION and ASAPO_BUILD_COMMIT.
• If not values are provided, CMake uses Git to calculates these values based on the last Git tag and current commit SHA.
• The values of ASAPO_VERSION, ASAPO_VERSION_COMMIT, PYTHON_ASAPO_VERSION, ASAPO_DOCKER_DEV_SUFFIX and ASAPO_DOCKER_TAG are calculated from ASAPO_VERSION and ASAPO_BUILD_COMMIT.
• These values are compared against the corresponding environment variables if defined, which is the case when the code is executed in GitLab CI.