feat: support passing arguments to plugin

[sxyazi]

You can now use the plugin command with --args for passing some arguments:

plugin your-plugin --args='foo bar'

Then receive them in your Lua code through args:

return {
  entry = function(self, args)
    ya.err(args[1]) -- "foo"
    ya.err(args[2]) -- "bar"
  end,
}