Is your feature request related to a problem? Please describe.
As substrait gains popularity other db engines have the capability to export their LogicalPlans to substrait. We should offer the ability for dask-sql to run those .proto substrait files directly from the dask-sql context.

Describe the solution you'd like
Add a flag to the Context.sql(..) method to treat the sql param as a path to a substrait proto file that should be ran directly without using the Datafusion planner.

Describe alternatives you've considered
None

Additional context
None