Teach structured errors to display short `Ty`

Make it so that every structured error annotated with `#[derive(Diagnostic)]` that has a field of type `Ty<'_>`, the printing of that value into a `String` will look at the thread-local storage `TyCtxt` in order to shorten to a length appropriate with the terminal width. When this happen, the resulting error will have a note with the file where the full type name was written to.

```
error[E0618]: expected function, found `((..., ..., ..., ...), ..., ..., ...)``
 --> long.rs:7:5
  |
6 | fn foo(x: D) { //~ `x` has type `(...
  |        - `x` has type `((..., ..., ..., ...), ..., ..., ...)`
7 |     x(); //~ ERROR expected function, found `(...
  |     ^--
  |     |
  |     call expression requires function
  |
  = note: the full name for the type has been written to 'long.long-type-14182675702747116984.txt'
  = note: consider using `--verbose` to print the full type name to the console
```

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 8e5ff1d3bc4..ecdf76d22fb 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -109,8 +109,8 @@ impl Mul<usize> for Limit {
 }
 
 impl rustc_errors::IntoDiagArg for Limit {
-    fn into_diag_arg(self) -> rustc_errors::DiagArgValue {
-        self.to_string().into_diag_arg()
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> rustc_errors::DiagArgValue {
+        self.to_string().into_diag_arg(&mut None)
     }
 }