Detect more cases of `=` to `:` typo
When a `Local` is fully parsed, but not followed by a `;`, keep the `:` span arround and mention it. If the type could continue being parsed as an expression, suggest replacing the `:` with a `=`.
```
error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
--> file.rs:2:32
|
2 | let _: std::env::temp_dir().join("foo");
| - ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
| |
| while parsing the type for `_`
| help: use `=` if you meant to assign
```
Fix#119665.
