Refactor compiler package to use optimized Value struct

[jsternberg]

We are going to refactor the compiler package to use an optimized Value struct as detailed in this proposal. Instead of refactoring the Value interface, we will be creating a new Value struct in the compiler package and modifying the compiler package to use this instead of values.Value.

Note: This should be done through copying the package into a new package below internal. We then want to feature flag the use of this new compiler in areas where the old compiler is used.

DOD:

• A refactored compiler exists that uses a Value struct as described in the above proposal.
• It is behind a feature flag (either scoped to map or the compiler)
• Tests should be testing with the flag on and off

[jsternberg]

Not going to be done. We're more likely to completely replace the compiler package with an alternative so this issue won't get done.