InlayHint textEdits are not always correct

[adam-fowler]

The text edits supplied with InlayHints don't always provide code that will compile eg adding the inlay hint to a closure argument would generate invalid code

func test(_ process: (String) -> ()) {
    process("hello")
}
test { string in 
    print(string)
}

The inlay hint for string is : String. The text edit that goes along with it is the same and inserting it would generate the following code

test { string: String in
    print(string)
}

which does not compile.

Another example is enums with associated values

case .test(let value):

becomes

case .test(let value: (String)):

Maybe we should disable the text edit option until we can be sure it returns valid code.

See swiftlang/vscode-swift#554 where this was originally reported

[ahoppen]

Tracked in Apple’s issue tracker as rdar://111559715