[SPI-1909] build docker containers in gitlab CI

• This adds configuration to run the docker build in gitlab CI.
• Only jobs are available for platforms where the build/<PLATFORM>/* files were changed, but they still need to be triggered manually.
  • This could be changed to automatically build the containers were files have changed.
• added cmake to the centos8 container packages to make the test pass (this was also failing in the jenkins job). Note that for centos8 also the make isn't found, which isn't triggering an error. Also in the jenkins job make is found but not the version installed previously.