Rollup merge of #68705 - BijanT:ll_remove, r=Mark-Simulacrum
Rollup merge of #68705 - BijanT:ll_remove, r=Mark-Simulacrum

Add LinkedList::remove()

LinkedList::remove() removes the element at the specified index and returns it.

I added this because I think having a remove function would be useful to have, and similar functions are in other containers, like Vec and HashMap.

I'm not sure if adding a feature like this requires an RFC or not, so I'm sorry if this PR is premature.

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