Add multiple independent sign banks

[AmitMY]

• BSL: https://bslsignbank.ucl.ac.uk/dictionary/
• ASL: https://aslsignbank.haskins.yale.edu/signs/show_all/
• NGT: https://signbank.cls.ru.nl/signs/show_all/
• Finnish: https://signbank.csc.fi/dictionary/
• Auslan: https://auslan.org.au/dictionary/search/?query=A&category=
• NZSL: https://www.nzsl.nz/
• Polish: https://www.slownikpjm.uw.edu.pl/en
• SGSL: https://blogs.ntu.edu.sg/sgslsignbank/signs/
• Asian: http://cslds.org/asiansignbank/