Add .luau support to RojoResolver

[osyrisrblx]

Converts input paths from .lua -> .luau internally to better handle results of PathTranslator.getImportPath().

[sasial-dev]

Should we use this PR to also support the others file extensions rojo supports natively?
I believe only .toml is missing, as YAML support is in another PR (rojo-rbx/rojo#913) that we can do later.

[osyrisrblx]

.toml is an interesting thought.. however, TypeScript doesn't have built-in support for this like it does for JSON files, so I'm not sure it would do you a ton of good.

You could potentially make a .d.ts file with:

declare module "*.toml" {
	const value: unknown;
	export default value;
}

This would allow you to import any .toml file, but the import would just be unknown.

I don't think that gives you much value. You could just require() the rojo-made ModuleScript and get the same thing.

Alternatively, you might be able to use a TypeScript plugin like:
https://github.com/sapphi-red/typescript-plugin-toml

This seems to work okay for me in the editor, but the compiler throws an error saying it can't find the module. We'd probably need to add support for these plugins somehow.