`filter_level` and `language` for sample stream requests

[tesaguri]

trafficstars

https://developer.twitter.com/en/docs/tweets/filter-realtime/guides/basic-stream-parameters

filter_level

This parameter may be used on all streaming endpoints, unless explicitly noted.

language

This parameter may be used on all streaming endpoints, unless explicitly noted.

GET statuses/sample can take these parameters, too. It would be great if egg_mode::stream::sample provided interface for them.