Rollup merge of #143967 - oli-obk:const-option-methods, r=fee1-dead

constify `Option` methods

r? ```````@fee1-dead```````

tracking issue: rust-lang/rust#143956

these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

Author: matthiaskrgr