Add badges

What is the new feature

Add badges

How is it implemented

Adding to README. Pipelines for master branch has to be enabled for pipeline and coverage badges to show.

• This MR has to wait for !57 (merged)

Mandatory steps before review

• Gitlab CI passes (Hint: use make format for linting)
• New feature is covered by additional unit tests
• Mark the merge request as ready by removing Draft:

Mandatory steps before merge

• Reviewed by a maintainer
• Incorporate review suggestions
• Remember to edit the commit message and select the proper changelog category (feature/bugfix/other)

You are not supposed to merge this request by yourself, the maintainers of fortan-support take care of this action!