Rollup merge of #133696 - RalfJung:const-hashmap, r=cuviper

stabilize const_collections_with_hasher and build_hasher_default_const_new

After a lot of preparatory work, finally we can stabilize creating `HashMap` in const context. :)

FCP for const_collections_with_hasher passed in rust-lang/rust#102575.
Fixes rust-lang/rust#102575.

FCP for build_hasher_default_const_new passed in rust-lang/rust#123197.
Fixes rust-lang/rust#123197.

Cc `@Amanieu`
Release notes: rust-lang/rust#133347

Author: matthiaskrgr