SQL planner should use `TableSource` not `TableProvider`

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
SQL planner should use TableSource not TableProvider since there is no need to actually perform scans during planning and this would be a step towards moving the SQL planner into its own crate so we have cleaner dependency management,

Describe the solution you'd like
SQL planner should use TableSource not TableProvider

Describe alternatives you've considered
None

Additional context
None