[fix] dailymotion engine: filter by language & country

- fix the issue of fetching more the 7000 *languages*
- improve the request function and filter by language & country
- implement time_range_support & safesearch
- add more fields to the response from dailymotion (allow_embed, length)
- better clean up of HTML tags in the 'content' field.

This is more or less a complete rework based on the '/videos' API from [1].
This patch cleans up the language list in SearXNG that has been polluted by the
ISO-639-3 2 and 3 letter codes from dailymotion languages which have never been
used.

[1] https://developers.dailymotion.com/tools/

Closes: https://github.com/searxng/searxng/issues/1065


Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>