Support transactions

[vwkd]

Support transactions in the Query Editor.

start transaction;
select "hello world";
commit;

Currently, it fails with an error.

DisabledCapabilityError: cannot execute transaction control commands: disabled by the client

The CLI in contrast supports it.

This is useful, because the Web UI is a simple and convenient way to edit new queries and test them out.

[Arrow7000]

I've run into this several times, it would be really nice if the UI wasn't limited in this way