Add command to format json files in project to just format recipe

[kerber0x]

just fmt formats rust, toml and bash files, but not json. Add that one to the recipe.

[kerber0x]

It can be easily done with

npx prettier@2.7.1 --$op "./**/*.json" similarly to how it's done for md files in format_md.sh, the problem is that it formats everything, including schemas (which should probably be ignored).