Add test with ASAN enabled.

[Rot127]

Your checklist for this pull request

• [ ] I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• [x] I've added tests that prove my fix is effective or that my feature works (if possible)

Detailed description

Add ASAN builds

It does a few things

• Fix a lot of mem leaks,
• Add ASAN to the CI (this also removes the make build from the CI), because I did not want to add ASAN for a build type we consider deprecated. This can be debated and I can add it without ASAN support again.
• Fix the build of cstest via CMakeLists.txt. This allows now also to enable ASAN for the cstest. Also it is much easier to build cstest now.
• Fixes cstest-report.py to work also when cstest is installed and in PATH.
• Make run_invalid_cstool.sh more verbose to help spotting possible ASAN errors.
• Add and fix tests/cs_details/issue.cs to the CI.

Test plan

CI green (or, if everything fails horribly, mark it optoinal for now)

Closing issues

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