Prior to this PR, when we aborted because a "critical pass" failed, we
displayed the number of errors from that critical pass. While that's the
number of errors that caused compilation to abort in *that place*,
that's not what people really want to know. Instead, always report the
total number of errors, and don't bother to track the number of errors
from the last pass that failed.
This changes the compiler driver API to handle errors more smoothly,
and therefore is a compiler-api-[breaking-change].
Fixes#42793.
Add a `TyErr` type to represent unknown types in places where
parse errors have happened, while still able to build the AST.
Initially only used to represent incorrectly written fn arguments and
avoid "expected X parameters, found Y" errors when called with the
appropriate amount of parameters. We cannot use `TyInfer` for this as
`_` is not allowed as a valid argument type.
Example output:
```rust
error: expected one of `:` or `@`, found `,`
--> file.rs:12:9
|
12 | fn bar(x, y: usize) {}
| ^
error[E0061]: this function takes 2 parameters but 3 parameters were supplied
--> file.rs:19:9
|
12 | fn bar(x, y) {}
| --------------- defined here
...
19 | bar(1, 2, 3);
| ^^^^^^^ expected 2 parameters
```
