Support for JSON5

[Niols]

Is your feature request related to a problem? Please describe.

As a human, I very much like JSON5. It is all one wishes JSON was but isn't. I wish Topiary would support formatting it. I expect it shouldn't be very hard, if there is already an existing grammar.

Additional context

https://json5.org/

[Xophmeister]

Yes, it should be pretty straightforward. I found this grammar, so we should be all set.

[Xophmeister]

I gave this a go, in #954, but the grammar doesn't support line breaks inside strings. I'll take a look at the grammar to see how easy it would be to add this... 🤞

[Niols]

Fingers crossed indeed!