make setup.sh completely non-interactive

[georglauterbach]

Description

Cleans up setup.sh and makes it possible to use the script in a completely non-interactive way. Added -R flag. Moved ENV variables to the top, removed unnecessary functions and renamed functions.

This PR should be the last one added to the 10.2.0 milestone. This PR is not a breaking change. Fixes a regression for SELinux (used OPTARG where OPT was actually correct).

Follow up on #2179

Type of change

• Improvement (non-breaking change that does improve existing functionality)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[polarathene]

Nice improvements! ❤️

[georglauterbach]

@polarathene I removed one line from the .ecrc file for the EditorConfig lint, but the line with "^test/" will still block the whole test directory. I will take care of that with another PR.

[casperklein]

No show-stopper. But I was wondering, why you chose an upper-case 'R'. With the exception of -Z, all other parameters are lower-case.

[georglauterbach]

The full story is this: I war originally trying to use --rootless, but since getopts does not care about double-dashed flags, and I did not want to increase the complexity of the script, I figured I should go with a single-letter-option. When I used r - and I did in the beginning - I always found myself reminded of --recursive and I knew some scripts where using an uppercase letter to denote that there is a long version available, so I chose -R (without a long version availabe). Feel free to change this with another small PR before v10.2.0 is released if you think this is incorrect - I'd just like to get this PR merged :)