Fix a bunch of typo

This PR will fix some typos detected by [typos].

I only picked the ones I was sure were spelling errors to fix, mostly in
the comments.

[typos]: https://github.com/crate-ci/typos

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -430,7 +430,7 @@ impl TtParser {
                     }
                 }
                 MatcherLoc::Delimited => {
-                    // Entering the delimeter is trivial.
+                    // Entering the delimiter is trivial.
                     mp.idx += 1;
                     self.cur_mps.push(mp);
                 }