feat(primitives): implement map module

[DaniPopes]

Add mod map in alloy-primitives which contains type aliases for different hashmaps with different hashers.

Contains a set of:

• hashmap, hashset (from hashbrown or std); indexmap, indexset
• default hasher, fxhash
• fixed-bytes hasher for FixedBytes and aliases

Default hasher is: fxhash random seed ("map-fxhash" + "std" + "rand") > fxhash no seed ("map-fxhash") > std > hashbrown default hasher
(can't have random seed in no_std AFAICT)

New features:

• "map" - enables the module
• "map-fxhash" - switches default hasher to fxhash and re-exports
• "map-hashbrown" - forces HashMap to be a re-export of hashbrown instead of std (default for no_std)
• "map-indexmap" - indexmap re-exports
• "nightly" - passes through "nightly" to dependencies, useful for enabling override of Hasher::write_length_prefix

[mattsse]

cool, this should be useful

the stable build error looks odd

[DaniPopes]

It's due to "nightly" feature due to --all-features on stable