Previously this was logged to the console when running tests:
```
[ParseError] Parsing a `DeclSyntax` node from string interpolation produced the following parsing errors.
Set a breakpoint in `SyntaxParseable.logStringInterpolationParsingError()` to debug the failure.
```
And slightly improve the style of the expanded `@SwiftSyntaxRule` macro.
These macros remove some of the boilerplate involved when writing rules.
This change also adds test infrastructure for the macros used within
SwiftLint.
Danny Mösch
JP Simard