feat: show dry-run preview of what would be pushed to child repo in metta publish

[yatharth]

Instead of just saying we would push filtered history to the child repo, we can actually show a dry run output of exactly what would be pushed.

Asana Task

[yatharth]

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• feat: prompt user to publish public announcement in discord during metta publish #4527
• feat: run cogames smoke test from source code in child repo #4523
• refactor: reorder jobs in release-cogames.yml to be in execution order #4525
• feat: include package-specific tags in filtered history pushed to child repo during metta publish #4522
• feat: show dry-run preview of what would be pushed to child repo in metta publish #4521 👈 (View in Graphite)
• feat: add smoke test in cogames release workflow #4423
• fix: smoke test caught undeclared dependency on uv in cogames tests #4425
• fix: remove all imports from metta in cogames #4421 : 1 other dependent PR (#4422 )
• 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
• refactor: reorganise metta publish.py to prepare for downstream refactor #4415
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