Issue Description:

When creating a new type that conforms to ExpressibleByStringLiteral (or extending an existing type to conform), there is initially a “does not conform” error with a fixit to add a typealias. After accepting that fixit and completing the typealias, I would expect another error with a fixit to add a stub for the init(stringLiteral:) method.

However, instead of a “does not conform” error, there is a very different error and no fixit:

struct Foo: ExpressibleByStringLiteral {
  typealias StringLiteralType = String
}
// Error: Initializer 'init(extendedGraphemeClusterLiteral:)' has different argument labels from those required by protocol 'ExpressibleByStringLiteral' ('init(stringLiteral:)')