Feature request: `dolt sql` should have a flag which lets it fast fail if the database is read-only

As per #10852, some callers might prefer the CLI invocation to fast-fail, instead of waiting until an incoming SQL statement actually tries to perform a write against the database.

Start at the `dolt sql` CLI entry point and trace how it opens or detects read-only databases. Review #10852 for the existing read-only behavior, then define the flag's failure timing and add coverage showing that a read-only invocation fails before executing a write statement.

Written by the indexing model from the issue text.