Normalize generated preCICE data names

[alloutflo]

Summary

• rename the generated load-balancing scalar from rank_of_sim to Rank-Of-Sim
• rename the generated model-adaptivity scalar from model_resolution to Model-Resolution
• keep configuration registration and runtime output keys in sync
• document both required preCICE data names and record the breaking change
• add regression coverage for configuration, load-balancing output, and model-adaptivity output

Fixes #317

Root cause

The two optional outputs were registered in the Micro Manager configuration and emitted at runtime under snake_case names, while the other generated preCICE data names use the documented title-case, hyphenated convention. Changing only one side would make the configured write-data name disagree with the actual output dictionary, so this updates both paths together.

Validation

• python -m unittest test_micro_manager.py test_model_adaptivity.py test_load_balancing.py — 18 tests passed, 6 parallel-only tests skipped in the serial run
• mpiexec -n 2 python -m unittest test_load_balancing.py — passed on both ranks
• mpiexec -n 4 --oversubscribe python -m unittest test_load_balancing.py — passed on all four ranks
• pre-commit run --all-files --verbose — all hooks passed
• git diff --check — clean

Checklist:

• I made sure that the CI passed before I ask for a review.
• If this is a use-side change, I added a summary of the changes (compared to the last release) in the CHANGELOG.md. If this is a breaking change, I wrote breaking change at the end of the changelog entry.
• If necessary, I made changes to the documentation and/or added new content.
• I will remember to squash-and-merge and provide a useful summary of the changes of this PR.