[console] Add a read-only flag to run_sql

While working with a read-only database, using run_sql is not possible because the default transaction mode is read-write and isn't read-only. I can work around this by manually setting the "read_ony" flag to true in the API call.

Given that Hasura now works with read-only databases, making Hasura console work well with read only databases could be an overall umbrella issue that we start tracking as well!

Start at the Hasura console's run_sql entry point and trace the API request it sends, using the issue's read-only database scenario as the first case to reproduce. Done means the console can pass a read-only setting for run_sql and the request works against a read-only database.

Written by the indexing model from the issue text.