Auto merge of #33318 - alexcrichton:hashmap-seed, r=aturon

Auto merge of #33318 - alexcrichton:hashmap-seed, r=aturon

std: Cache HashMap keys in TLS

This is a rebase and extension of #31356 where we not only cache the keys in
thread local storage but we also bump each key every time a new `HashMap` is
created. This should give us a nice speed bost in creating hash maps along with
retaining the property that all maps have a nondeterministic iteration order.

Closes #27243