This is a POC for blocknote-level transactions. It should make it possible to clean our existing commands (those in blockManipulation further down by migrating away from tiptap-style commands). It also unlocks the possibility for userland-transactions.

For example, the following bug is fixed:

• select a number of paragraphs
• change type to "heading"
• "undo" will undo them one by one (after the fix, "undo" will reset all headings back to paragraphs in one step as expected)

closes https://github.com/TypeCellOS/BlockNote/issues?q=is:issue is:open undo

TODO:

• add tests
• See if there are bugs with this approach. For example, what if you call other functions in a transact block that depend on editor.state? It's likely they should read the state from the activeTransaction instead (diagnose, create tests, and fix)
• if there are other BlockNote APIs called in a loop (similar to blocktype select), migrate them to use transact