Merge #9807

9807: Implicit `Sized` bounds r=iDawer a=iDawer

This should close #8984 

`hir_ty`:
- Type parameters, associated types and `impl Trait` are `Sized` by deafault except `Self` in a trait.
- Implicit `Sized` bound is added to end of predicate list. It does not check if such bound is present already. Also it does not track the bound is implicit.
- Allowed ambiguous unsize coercion if Chalk returns definite guidance.
- Allowed ambiguous autoderef if Chalk returns definite guidance.

`hir_def`:
- `ItemTree` pretty printing shows `?Sized` bounds.

`HirDisplay`:
- `impl Trait` with weird bounds rendered correctly.
- `Sized`/`?Sized` bounds are not shown if they are default.

### Perf
`./target/rust-analyzer-baseline_8a843113 -q analysis-stats --memory-usage .`
```
Database loaded:     1.63s, 287minstr, 91mb
  crates: 38, mods: 741, decls: 15914, fns: 11835
Item Collection:     26.80s, 73ginstr, 338mb
  exprs: 318994, ??ty: 398 (0%), ?ty: 435 (0%), !ty: 174
Inference:           50.28s, 116ginstr, 516mb
Total:               77.08s, 189ginstr, 855mb
```

`./target/rust-analyzer-sized-fixed_ambig_coercion-de074fe6 -q analysis-stats --memory-usage .`
```
Database loaded:     1.63s, 287minstr, 91mb
  crates: 38, mods: 741, decls: 15914, fns: 11835
Item Collection:     26.95s, 73ginstr, 338mb
  exprs: 318994, ??ty: 398 (0%), ?ty: 435 (0%), !ty: 166
Inference:           96.39s, 234ginstr, 543mb
Total:               123.33s, 307ginstr, 881mb
```


Co-authored-by: Dawer <7803845+iDawer@users.noreply.github.com>

0 files changed, 0 insertions, 0 deletions