Refactor mapping tester using snake style naming

[kursatyurt]

Main changes of this PR

Refactoring mapping tester using snake naming convention. It follows the preCICE convention

C++ codes -> CamelCase
Python Scripts -> snake_case

Author's checklist

• I used the pre-commit hook and used pre-commit run --all to apply all available hooks.
• I added a test to cover the proposed changes in our test suite.
• I updated the documentation in docs/README.md.
• I updated potential breaking changes in the tutorial precice/tutorials/aste-turbine.

[davidscn]

Can you have a look at the failing tests?

I'm not too sure about renaming the python scripts as well. Note that the generate script generates runall.sh as well as postprocessall.sh. Do you also want to rename these files then? Maybe a better name for generate_mapping_test would be generate_mapping_test_cases?

[davidscn]

Suggested change

	python3 "${MAPPING_TESTER}"/prepare_mapping_teest_meshes.py --setup "${TEST_LOCATION}"/setup-test.json --outdir "${TEST_CASE_LOCATION}" --force
	python3 "${MAPPING_TESTER}"/prepare_mapping_test_meshes.py --setup "${TEST_LOCATION}"/setup-test.json --outdir "${TEST_CASE_LOCATION}" --force