Add flags to node build for selecting server repo and branch

[andrebastosdias]

Add flags to node build to specify the server's repository and branch. It should also detect whether the current caches/pokemon-showdown matches the ones specified in the flags.

pokemon-showdown-client/build-tools/build-indexes

Lines 11 to 15 in cc96065

	if (!fs.existsSync('caches/pokemon-showdown')) {
	child_process.execSync('git clone https://github.com/smogon/pokemon-showdown.git', {
	cwd: 'caches',
	});
	}