Auto merge of #45152 - Binero:master, r=dtolnay
Auto merge of #45152 - Binero:master, r=dtolnay

Addressed issues raised in #44286. (`OccupiedEntry::replace_entry`)

This commit renames the `replace` function to `replace_entry`, and
creates a seperate `replace_key` function for `OccupiedEntry`. The
original `replace` function did not solve the use-case where the
key needed to be replaced, but not the value. Documentation and
naming has also been updated to better reflect what the original
replace function does.

GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust