Migrate Debian Buster, Ubuntu Bionic to new build-all scripts

[kbgl]

To simplify maintenance and usage migrate Debian Buster and Ubuntu Bionic to new build-all scripts.
Work is started on migrate-deb-to-new-build-env branch.
Requires merging RHEL changes first.

• add environment files
• add verify functionality to build-all scripts
• add deprecation information to old scripts
• merge README.rhel.md and README.md

I think we can keep both scripts for some time, then do cleanup:

• remove old scripts
• move Dockerfiles and other image related files to build-env/target/*/*

Closing this will also close #101.

[ryannowarm]

@kbgl , can we close this?

[kbgl]

@ryannowarm we still have old scripts in repo. As for moving docker files this is not mandatory. Anyway we can close #101 now.