Add .jsonc file extension support

[NinjaMandalorian]

For #1144 to work fully with rojo, the .jsonc file extension should be supported for both

• project.json(c) files
• .json(c) config files that are translated to lua in-studio

Currently rojo serve does not recognise .jsonc, and all .jsonc files are ignored in syncing

[shysolocup]

YESS PLEASEE

[Dekkonot]

This was resolve in #1159 but I forgot to link it. This will be fixed in the next release.