Adds support for immovable generators. Move checking of invalid borrows across suspension points to borrowck. Fixes #44197, #45259 and #45093.

It is also intended for use with unions.

The Generics now contain one Vec of an enum for the generic parameters,
rather than two separate Vec's for lifetime and type parameters.

Additionally, places that previously used Vec<LifetimeDef> now use
Vec<GenericParam> instead.

This commit adds support for nested groups inside `use` declarations,
such as `use foo::{bar, sub::{baz::Foo, *}};`.

closes https://github.com/nrc/rls-analysis/issues/117

Use the span we save in the PathSegment for a method call, rather than searching for it in the text.

Fixes https://github.com/nrc/rls-analysis/issues/111

Adds an `IsAuto` field to `ItemTrait` which flags if the trait was
declared as an `auto trait`.

Auto traits cannot have generics nor super traits.

Fixes https://github.com/nrc/rls-analysis/issues/78

fixes https://github.com/nrc/rls-analysis/issues/52

This special cases the function type sugar in paths and deals with traits bounds as just the path parts. That required refactoring the path collector to distinguish between variable decls and references in patterns, basically just to please the borrow checker.

cc https://github.com/nrc/rls-analysis/issues/37

Lifting Generics from MethodSig to TraitItem and ImplItem since we want to support generics in each variant of TraitItem and ImplItem

0.10 -> 0.11

This will allow for more fine-grained save analysis for enum variants
(tuple and struct)

Like #43008 (f6689991), but _much more aggressive_.

Use the `span` field in PathSegment and TyParam instead.

Fix #43796. Close #41478.