Support a configurable source for trino #5671

It is beneficial to us to be able to modify the X-Trino-Source field when running sqlmesh. This can be leveraged for query attribution / auditing or other routing and configuration solutions.

this field is configurable in trino, but sqlmesh does not expose it for configuration, and it is always hardcoded as sqlmesh.

Request - add a configuration option for this field, use it if defined, or fall back to current sqlmesh default if not.