Auto merge of #116666 - Urgau:check-cfg-pre-mcp636, r=petrochenkov

Improve check-cfg diagnostics

This PR tries to improve some of the diagnostics of check-cfg.

The main changes is the unexpected name or value being added to the main diagnostic:
```diff
- warning: unexpected `cfg` condition name
+ warning: unexpected `cfg` condition name: `widnows`
```

It also cherry-pick the better sensible logic for when we print the list of expected values when we have a matching value for a very similar name.

Address rust-lang/rust#111072 (comment)

r? `@petrochenkov`

Author: bors