Shorten some error invocations.

- `struct_foo` + `emit` -> `foo`
- `create_foo` + `emit` -> `emit_foo`

I have made recent commits in other PRs that have removed some of these
shortcuts for combinations with few uses, e.g.
`struct_span_err_with_code`. But for the remaining combinations that
have high levels of use, we might as well use them wherever possible.

compiler/rustc_builtin_macros/src/source_util.rs

@@ -155,7 +155,7 @@ pub fn expand_include<'cx>(
                         if self.p.token != token::Eof {
                             let token = pprust::token_to_string(&self.p.token);
                             let msg = format!("expected item, found `{token}`");
-                            self.p.dcx().struct_span_err(self.p.token.span, msg).emit();
+                            self.p.dcx().span_err(self.p.token.span, msg);
                         }
 
                         break;