Add auto language detection

[Dankoy]

Is your feature request related to a problem? Please describe.
When user used "auto" as sourceLanguage key in command "anki-exporter", application skip dictionaryapi. It would be better to detect automatically which language is used before make decision to use dictionaryapi or not.

Describe the solution you'd like
Use Tika language detection to check whole vocabulary-builder database. Seems like it's correct to take one word in book as example word and detect language for whole book. As long as whole book read in one language is should be enough.

Describe alternatives you've considered
None

Additional context
None