More map types in EnumerableMap

[RyanRHall]

🧐 Motivation
Small feature request, but I would love if EnumerableMap would support an address => bytes32 and a uint256 => bytes32 mapping. I have several cases where this has been useful and I end up using a Bytes32ToBytes32Map and then casting the key to the type I want. It works fine, but it would be cleaner if we supported the more specific types :). Happy to help contribute the changes!

📝 Details
Hopefully the motivation section is sufficiently clear :)

[ernestognw]

Hey @RyanRHall , I've seen a few Code4rena projects in the past using variations of EnumerableMap. This is relatively easy to implement since all variants come from a single template and perhaps there's demand.

I'm adding a 5.x tag to consider this for future releases if a good discussion comes up from here.

Note that any modification shouldn't be considered audited even if the other variants already are.