* Added @ts-expect-error to @ts-ignore directives
Similar to `// @ts-ignore`, but will itself cause a new error diagnostic if it does not cause an existing diagnostic to be ignored.
Technical summary:
1. The scanner will now keep track of `CommentDirective`s it comes across: both `@ts-expect-error` and `@ts-ignore`
2. During type checking, the program will turn those directives into a map keying them by line number
3. For each diagnostic, if it's preceded by a directive, that directive is marked as "used"
4. All `@ts-expect-error` directives not marked as used generate a new diagnostic error
* Renamed to getDiagnosticsWithPrecedingDirectives per suggestion
* Added JSDoc comment I thought I did already
Co-authored-by: Orta <orta.therox+github@gmail.com>
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