Add `merge.squash`

[mitchellwrosen]

[aryairani]

Could you link to the deleted transcript for merge.squash.old if you think there's a chance we'll want to resurrect it after adding this

[aryairani]

I guess they're represented as individual commits here https://github.com/unisonweb/unison/pull/5138

[ceedubs]

Could you link to the deleted transcript for merge.squash.old if you think there's a chance we'll want to resurrect it after adding this

Hmm has that been deleted? I still use that as per Arya's recommendation last week https://github.com/unisonweb/unison/issues/5099#issuecomment-2174881761

[aryairani]

Could you link to the deleted transcript for merge.squash.old if you think there's a chance we'll want to resurrect it after adding this

Hmm has that been deleted? I still use that as per Arya's recommendation last week #5099 (comment)

@ceedubs Only the transcript was deleted; it needs to be updated for the removal of loose code, and then it wasn't clear whether it would be better to write a new scenario for merge.squash.old or implement merge.squash[.new]

The latter would need to support

@me/app/branch> merge.squash @x/foo/jun_17 lib.x_foo_jun_17

unless there's a replacement workflow for you.