Support for `--resource` flag

[lwronski]

Is your feature request related to a problem? Please describe.
For now, Scala CLI supports only --resource-dir flags, which allows specifying resources directory. It would be nice, if it will be available new flag --resource to pass resources file instead of whole directory.

[Gedochao]

Currently worked on by @yadavan88

[yadavan88]

@Gedochao 👍