Format sublime's settings files

[niosus]

Hey @dzhibas I was wondering if it would be hard to extend the formatter to support sublime text's settings files. They mostly follow json convention, but allow trailing commas and comments in the file. Do you think it is possible?

[TerminalFi]

@niosus not possible with the current simplejson library. Not sure we'd want to move away from that as I don't believe there is a python library that supports jsonc. And when relying on non-python libraries you get slow results.