Rollup merge of #121615 - nnethercote:fix-121517, r=oli-obk

Move `emit_stashed_diagnostic` call in rustfmt.

This call was added to `parse_crate_mod` in #121487, to fix a case where a stashed diagnostic wasn't emitted. But there is another path where a stashed diagnostic might fail to be emitted if there's a parse error, if the `build` call in `parse_crate_inner` fails before `parse_crate_mod` is reached.

So this commit moves the `emit_stashed_diagnostic` call outwards, from `parse_crate_mod` to `format_project`, just after the `Parser::parse_crate` call. This should be far out enough to catch any parsing errors.

Fixes #121517.

r? `@oli-obk`
cc `@ytmimi`

Author: matthiaskrgr