Improved OBS autosubmission

[lslezak]

Problem

• Cannot submit other branches than master to OBS

Solution

• Make the GitHub Actions more generic, allow submitting any branch to any OBS project
• It works also with GitHub forks and OBS home repositories
• Added a script for creating a new OBS project

Details

• Run the actions for any branch or tag
• The actions use OBS_PROJECTS GitHub variable with mapping "Git branch/tag name" => "OBS project name"
• Removed creating automatic submit requests, that needs to be done manually
• See more details about the workflow in the new README.md file
• Added CI which runs shellcheck for the devel scripts

Testing

• Tested manually, I configured autosubmission using the branch2obs.sh script from "master" branch of my GitHub fork to newly created home:lslezak:Agama:branches:master project.