Function Overload Rework

[Hydrocharged]

What this adds:

• Type resolution for all extended (Doltgres) types
• Proper type casting between types (extendable to support user-defined conversion)
• Additional Types

The previous function overload framework only worked in a very limited capacity. This PR intends to remove those limitations, allowing for all current (and future) Postgres functions to be defined. In general, this is also designed to support user-defined functionality, or at least designed in such a way that it will be relatively easy to fully implement it later on.

Related PR: dolthub/dolt#7537

[Hydrocharged]

Build currently fails as I need to finish converting all of the functions over to the new framework. Also need to add more types. Neither of those will take long.

However, I'm still trying to find a good way to represent type conversions. varchar(255) and varchar(256) currently compare as different types, which is correct. However, they're the same base type, and I need to figure out a good solution for that which will work with conversions (i.e. map storage, etc.). In GMS we use query.Type for this purpose, which will work fine for the default types, but won't work for user-defined types.

[zachmu]

What's here looks fine, just some comments about the organization. Approving without passing tests assuming that changes will be minor, ping me if that's not the case

[Hydrocharged]

The replication tests will fail, but for the most part this is reviewable.

[zachmu]

LGTM

My main comment about this is that we need engine (server) tests for all the functions you defined. Make that a fast-follow to this.