Integrate DeepL into translate5 as an MT-resource.

The sections of the DeepL API that needs to be integrated are

Translating text
https://www.deepl.com/en/docs-api.html?part=translating_text

and

Listing supported languages
https://www.deepl.com/en/docs-api.html?part=other

Translating text

split_sentences must be "0" if used for matches/pretranslation and "1" when used in InstantTranslate

preserve_formatting must be "0"

tag_handling must be "xml" for matches/pretranslation and off for InstantTranslate

Other params are not needed.

Listing supported languages

This query should determine, which languages are offered for creating DeepL languageResources in translate5.