This PR adds types to the `crdt` directory to make the structure of the
merkle tree (really a merkle radix trie) clearer.

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Co-authored-by: Jed Fox <git@jedfox.com>
Co-authored-by: Matiss Janis Aboltins <matiss@mja.lv>

actual-server does not need to import the full actual-app/api package.
It can import only the CRDT stuff.. so I'm extracting it into a new
package to reduce the size of actual-server and make the link between
things more transparent.

Another batch of `loot-core` migrated.

*  (prettier) adding trailing commas

* More commas

* style: enforce sorting of imports

* style: alphabetize imports

* style: merge duplicated imports