Allow functions to not be included in the emitted interface

[pengux]

What do you want to change?

When the setting emit_interface: true is set, all functions are included in the generated Querier interface. There should be a away to exclude certain functions from the interface. The use case is when you have extra code in the same package that may use unexported functions.

What database engines need to be changed?

No response

What programming language backends need to be changed?

Go