Modify nightly build script to avoid maintaining a separate branch

[metacosm]

What needs to be done:

• checkout out main
• update the version to 999.F8-SNAPSHOT
• update JOSDK version use 999.F8-SNAPSHOT version
• retrieve dynamically the latest SNAPSHOT version for the fabric8 client
• add kubernetes-client-bom to the BOM section of the build-parent POM
• run release script

Things that are currently not easily achieved / done are retrieving the latest fabric8 version automatically and adding the bom to the build parent.

[metacosm]

Actually, the build script would need to be either embedded or modified because it checks out a named branch so we'd need to either make it run on an existing checkout or make it able to run pre-processing script on the checked out branch before starting the actual build so that the main branch checkout could be modified according to the steps outlined in the issue description.

[metacosm]

Maybe use https://github.com/l2x6/pom-tuner to modify the main branch on the fly?

[metacosm]

A lot of this has already been implemented but the snapshot release aspect is not solved.