Fixes rust-lang#66667

Previously, we called `tcx.typeck_tables_of` when determining whether or
not to emit a suggestion for a type error. However, we might already be
type-checking the `DefId` we pass to `typeck_tables_of` (it could be
anywhere in the query stack).

Fortunately, we only need the function signature, not the entire
`TypeckTables`. By using `tcx.fn_sig`, we avoid the possibility of cycle
errors while retaining the ability to emit a suggestion.

…anup, r=eddyb

Remove framework in `dataflow/mod.rs` in favor of "generic" one

This is the culmination of the work described in rust-lang/compiler-team#202. All dataflow analyses (including the one in `clippy`) have been ported to use the framework in `dataflow/generic`, which can efficiently handle both gen/kill and generic problems. This PR moves the framework in `dataflow/generic` to `dataflow/framework`, and removes the gen/kill framework in `dataflow/mod.rs`.

More comprehensive documentation for the new framework is tracked in rust-lang/rustc-dev-guide#564.

`clippy` will need to change the path it uses to import the dataflow analysis traits.

…arkor

Fix cycle error when emitting suggestion for mismatched `fn` type

Fixes rust-lang#66667

Previously, we called `tcx.typeck_tables_of` when determining whether or
not to emit a suggestion for a type error. However, we might already be
type-checking the `DefId` we pass to `typeck_tables_of` (it could be
anywhere in the query stack).

Fortunately, we only need the function signature, not the entire
`TypeckTables`. By using `tcx.fn_sig`, we avoid the possibility of cycle
errors while retaining the ability to emit a suggestion.

Allow obtaining &mut OsStr

```rust
impl DerefMut for OsString {...}              // type Target = OsStr
impl IndexMut<RangeFull> for OsString {...}   // type Output = OsStr
```

---

This change is pulled out of rust-lang#69937 per @dtolnay

This implements `DerefMut for OsString` to allow obtaining a `&mut OsStr`. This also implements `IndexMut for OsString`, which is used by `DerefMut`. This pattern is the same as is used by `Deref`.

This is necessary to for methods like `make_ascii_lowercase` which need to mutate the underlying value.

Decouple `rustc_hir::print` into `rustc_hir_pretty`

High level summary:
- The HIR pretty printer, `rustc_hir::print` is moved into a new crate `rustc_hir_pretty`.
- `rustc_ast_pretty` and `rustc_errors` are dropped as `rustc_hir` dependencies.
- The dependence on HIR pretty is generally reduced, leaving `rustc_save_analysis`, `rustdoc`, `rustc_metadata`, and `rustc_driver` as the remaining clients.

The main goal here is to reduce `rustc_hir`'s dependencies and its size such that it can start and finish earlier, thereby working towards rust-lang#65031.

r? @Zoxc

Add regression test for rust-lang#66706

Adds the two cases that no longer ICE (rust-lang#66706 (comment))