[SR-12230] Improve diagnostic when enum case payload label doesn't match pattern

[jckarter]

Previous ID	SR-12230
Radar	rdar://problem/59655515
Original Reporter	@jckarter
Type	Task

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Task
Assignee	None
Priority	Medium

md5: e162e203353a4b22da300ab68cf02876

Issue Description:

If you have a label mismatch in an enum case pattern like this:

enum Foo {
  case foo(bar: Int)
  case bar
}

func switchFoo(x: Foo) {
  switch x {
  case .foo(bas: let bas):
    print("foo bas \(bas)")
  case .bar:
    print("bar")
  }
}

then you get an error like this:

/Users/jgroff/foo.swift:10:13: error: tuple pattern element label 'bas' must be 'bar'
  case .foo(bas: let bas):
            ^

But in the user's mental model, this isn't really a tuple pattern, they're trying to match against a particular enum case. Having an error with a note referring to the enum case would probably be easier to understand. Something like:

/Users/jgroff/foo.swift:10:13: error: enum type 'Foo' has no case named `foo(bas:)`, did you mean `foo(bar:)`?
  case .foo(bas: let bas):
            ^
/Users/jgroff/foo.swift:2: note: case `foo(bar:)` declared here

[hborla]

@swift-ci create