Run rustfmt on tests/codegen/.

Except for `simd-intrinsic/`, which has a lot of files containing
multiple types like `u8x64` which really are better when hand-formatted.

There is a surprising amount of two-space indenting in this directory.

Non-trivial changes:
- `rustfmt::skip` needed in `debug-column.rs` to preserve meaning of the
  test.
- `rustfmt::skip` used in a few places where hand-formatting read more
  nicely: `enum/enum-match.rs`
- Line number adjustments needed for the expected output of
  `debug-column.rs` and `coroutine-debug.rs`.

tests/codegen/debug-column.rs

@@ -3,6 +3,7 @@
 //@ ignore-windows
 //@ compile-flags: -C debuginfo=2
 
+#[rustfmt::skip]
 fn main() {
     unsafe {
         // Column numbers are 1-based. Regression test for #65437.
@@ -13,8 +14,8 @@ fn main() {
         // CHECK: call void @turtle(){{( #[0-9]+)?}}, !dbg [[B:!.*]]
 /* ż */ turtle();
 
-        // CHECK: [[A]] = !DILocation(line: 10, column: 9,
-        // CHECK: [[B]] = !DILocation(line: 14, column: 10,
+        // CHECK: [[A]] = !DILocation(line: 11, column: 9,
+        // CHECK: [[B]] = !DILocation(line: 15, column: 10,
     }
 }