Remove update.old

[ChrisPenner]

Overview

Removes update.old in favour of update

I've found myself rewriting a bunch of deprecated code for the project roots refactor, if it's reasonable to delete it it would be nice to do so now.

Implementation notes

• Removes update.old and update.old.preview
• Removes handleUpdate
• Rewrites all update.old in transcripts -> update

Interesting/controversial decisions

There are a few concerns about whether update.old can be removed, specifically Rúnar ran into some round-trip failures due to misformatted ability lists.

Test coverage

I updated the transcripts, I'd love if @mitchellwrosen could give them a look over though to ensure they still make sense.

[ChrisPenner]

Some re-ordering of constructor names here is strange, not sure if it's reason for concern.

[mitchellwrosen]

Hm, I'm not sure either

[ChrisPenner]

I patched this one up slightly, it was failing because builtins were out of scope.

[ChrisPenner]

I had to add this as well to prevent update from failing below.

[ChrisPenner]

I believe this block is something we don't care to test with update

[aryairani]

Just documenting that we have this on hold until people can use new update for everything.
However, as @ChrisPenner suggested, we could merge the transcript cleanup before merging the actual removal of the command; we don't need regression tests for the old functionality anymore.

[aryairani]

I'm thinking that even though it may not strictly be necessary to wait, that we get known round trip errors taken care of and before removing update.old and merge.old. This will increase my confidence that there's no unknown reason to keep them. 🙃