Currently solver picks the first conjunction it can find,
which means - the earliest resolved closure. This is not
always correct because when calls are chained closures
passed to the lower members could be resolved sooner
than the ones higher up but at the same time they depend
on types inferred from members higher in the chain.
Let's make sure that multi-statement closures are always
solved in order they appear in the AST to make sure that
types are available to members lower in the chain.
Detect situation when it's impossible to determine types for
closure parameters used in the body from the context. E.g.
when a call closure is associated with refers to a missing
member.
```swift
struct S {
}
S.foo { a, b in } // `S` doesn't have static member `foo`
let _ = { v in } // not enough context to infer type of `v`
_ = .foo { v in } // base type for `.foo` couldn't be determined
```
Resolves: [SR-12815](https://bugs.swift.org/browse/SR-12815)
Resolves: rdar://problem/63230293
all cases of missing generic parameters.
In `ComponentStep::take` when there are no bindings or disjunctions, use hole
propagation to default remaining free type variables that aren't for generic
parameters and continue solving. Rather than using a defaultable constraint for
holes, assign a fixed type directly when we have no bindings to try.
