Accept jsonc files for stadium files

[Wazarr94]

Given stadium files are actually jsonc files, would it be possible for you to allow jsonc files for custom stadiums?
Very small issue, but hbs stands for handlebars, which can cause confusion.

By using a jsonc file, IDEs such as vscode can provide help for formatting the map file as well.

[basro]

They are actually json5.

[Wazarr94]

They are actually json5.

Thanks for the precision. I don't much about the json alternatives