Improve recovery diagnostic for `for ( $pat in $expr ) $block`

[Centril]

Roughly according to #62928 (comment).

cc @estebank

[Centril]

Some notes:

We have two errors pointing at the problem here (the prior "in not expected" error, but it's ok emitting both for now)

I think this is not worth fixing as it would require hacks deep in the general sequence parser.

Suggestions that have very subtle changes sometimes make people not pay attention to the text, in this case people might not realize the lack of parenthesis in the suggested code.

We should try to still have MachineApplicable suggestions; @estebank notes that there are special purpose methods for doing that.

error: unnecessary parenthesis surroundinig for loop head

"Unnecessary" is semantically misleading here as this is a hard error, not a lint.