Update sqlite3_web, simplify

[simolus3]

This updates package:sqlite3_web to version 0.4.0. That version comes with a few new features, most notably:

1. OPFS support on Chrome without special headers! By using readwrite-unsafe as an opening mode when opening sync file handles, multiple tabs can open the same database concurrently. sqlite3_web will internally guard concurrent access with web locks to avoid contention on the file (since we still can't implement xLock synchronously).
2. Internal lock management. Since sqlite3_web needs locks for 1, those are now exposed in its API too. So, instead of using a custom protocol for lock management, we can just use sqlite3_web APIs here.
3. Automatic autocommit state checks: This package used to rely on custom requests for statements in transactions to verify the autocommit state before running statements in the transaction. Version 0.4.0 makes this simpler, since:
   • for database calls, we can pass checkInTransaction: true to make sqlite3_web reject the statement if the database is not in a transaction.
   • after each database call, we also get the autocommit state back automatically.

These features allow deleting a fair bit of logic here since we have that in slqite3_web now.

With these changes, new users on Chrome would get an OPFS database (it used to be IndexedDB before unless COOP + COEP headers were enabled):

There are checks in sqlite3_web ensuring that an IndexedDB database would be re-used if it exists.

[stevensJourney]

This is very nice. The added OPFS support option and removal of code here are very very cool.