Rollup merge of #134006 - klensy:typos, r=nnethercote

setup typos check in CI

This allows to check typos in CI, currently for compiler only (to reduce commit size with fixes). With current setup, exclude list is quite short, so it worth trying?

Also includes commits with actual typo fixes.

MCP: https://github.com/rust-lang/compiler-team/issues/817

typos check currently turned for:
* ./compiler
* ./library
* ./src/bootstrap
* ./src/librustdoc

After merging, PRs which enables checks for other crates (tools) can be implemented too.

Found typos will **not break** other jobs immediately: (tests, building compiler for perf run). Job will be marked as red on completion in ~ 20 secs, so you will not forget to fix it whenever you want, before merging pr.

Check typos: `python x.py test tidy --extra-checks=spellcheck`
Apply typo fixes: `python x.py test tidy --extra-checks=spellcheck:fix` (in case if there only 1 suggestion of each typo)

Current fail in this pr is expected and shows how typo errors emitted. Commit with error will be removed after r+.

compiler/rustc_ast/src/ast.rs

@@ -1344,7 +1344,7 @@ impl Expr {
         }
     }
 
-    /// Returns an expression with (when possible) *one* outter brace removed
+    /// Returns an expression with (when possible) *one* outer brace removed
     pub fn maybe_unwrap_block(&self) -> &Expr {
         if let ExprKind::Block(block, None) = &self.kind
             && let [stmt] = block.stmts.as_slice()

compiler/rustc_ast/src/visit.rs

@@ -142,7 +142,7 @@ macro_rules! common_visitor_and_walkers {
             )?
 
             // Methods in this trait have one of three forms, with the last two forms
-            // only occuring on `MutVisitor`:
+            // only occurring on `MutVisitor`:
             //
             //   fn visit_t(&mut self, t: &mut T);                      // common
             //   fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>;    // rare