refactor: simplify git and versioning logic in metta publish.py

[yatharth]

What this PR does

• Use built-in gitta methods over raw git command parsing (e.g., gitta.get_current_branch())
• Use keyword-only params to avoid call sites using wrong parameter order and to make refactors easier
• More explicit parameter names (e.g., skip_git_checks over force)
• Simpler control flow (consolidate if conditions, avoid double negatives in ifs)
• Prettier output (section headers, etc.)
• etc.

Asana Task

[yatharth]

• fix: remove all imports from metta in cogames #4421 : 2 dependent PRs (#4422 , #4425 )
• fix: manual dispatch of mettagrid/cogame release workflows was broken on certain branches #4419
• feat: wait for mettagrid PyPi release before publishing cogames to PyPi #4418
• feat: clearer warnings when using --force with metta publish #4516
• feat: pin cogames to specific mettagrid version before publishing #4417
• refactor: simplify git and versioning logic in metta publish.py #4416 👈 (View in Graphite)
• refactor: reorganise metta publish.py to prepare for downstream refactor #4415
• main

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