Implement static operator for splicing constants

[deusaquilus]

Want to be able to do (in an upstream compilation unit):

object PreCompileConstant {
  val SomeConst = "Blah"
}

And then...

quote { foo == static(PreCompileConstant.SomeConst) }

The value "Blah" should be spliced directly into the compile-time query. Quill should look it up and use it because it has already been compiled.

Additionally, there should be a want to implement this kind of splicing in a customizable way. If a user has a custom datatype (e.g. a custom enum), they should be able to create a implicit instance of a StaticSplice[MyDatatype]
(also in an upstream compilation unit) and then have the value of that automatically looked up and spliced into the compile-time sql query.