Allow custom modloader versions for auto curseforge

[SavePointSam]

Adds --fabric-loader-version, --forge-version, and --neoforge-version options to override modpack-declared modloader versions for install-curseforge command.

Partial fix for itzg/docker-minecraft-server#2653
Relates to itzg/docker-minecraft-server#3759

[itzg]

Thanks! Just wondering about combining.

[SavePointSam]

Updated to use a single option rather than loader specific ones

[itzg]

Just a nit pick remaining 😄

[itzg]

I feel pretty strongly about finals, so changing something to be un-final is almost a sin 😄

Now that the logic simpler, do it this way

Suggested change

	String loaderVersion = parts.length == 2 ? parts[1] : parts[2];
	// Override with custom versions if provided
	if (customModLoaderVersion != null) {
	log.info("Overriding mod loader version from {} to {}", loaderVersion, customModLoaderVersion);
	loaderVersion = customModLoaderVersion;
	}
	final String loaderVersion;
	// Override with custom versions if provided
	if (customModLoaderVersion != null) {
	log.info("Overriding mod loader version from {} to {}", loaderVersion, customModLoaderVersion);
	loaderVersion = customModLoaderVersion;
	}
	else {
	loaderVersion = parts.length == 2 ? parts[1] : parts[2];
	}