Rename the rule to something more general and without the deprecated TInstance in it.
Add a test to demonstrate the problem.
Fold UnionTypeCaster into TypeResolver.
Update rules to not reference that.
Since the union got the project spliced out, need to get the types from where they were put instead.
Disable the test that fails because of fundamental problems to be fixed shortly.
merge MMcM: Fold the Union type caster into the overload / type resolver.

Merge pull request #1183 from MMcM/sql-layer/sql-type-resolver-union
https://github.com/FoundationDB/sql-layer/pull/1183