Rollup merge of #91928 - fee1-dead:constification1, r=oli-obk

Constify (most) `Option` methods

r? ``@oli-obk``

Author: matthiaskrgr

core/src/lib.rs

@@ -123,6 +123,7 @@
 #![feature(const_num_from_num)]
 #![feature(const_ops)]
 #![feature(const_option)]
+#![feature(const_option_ext)]
 #![feature(const_pin)]
 #![feature(const_replace)]
 #![feature(const_ptr_is_null)]