Integrate ARASAAC and globalsymbols API for symbol search

[klues]

Just saw that cboard.io uses an API from https://globalsymbols.com/ for AAC symbol search. The advantage compared to currenty used opensymbols.org is, that search can be done in several languages, e.g. German.

I wrote a mail to globalsymbols.com contact asking for details about API usage.

[klues]

New plan after ARASAAC told us about their API:

• let user choose which symbol set they want to use (ARASAAC, Sclera, ...)
• if ARASAAC is chosen (default) use ARASAAC API: https://arasaac.org/developers/api
• for other symbol sets use globalsymbols API: https://globalsymbols.com/api/docs
• the ID of the chosen image should be saved in order to use features like changing skin color etc. afterwards/globally

[klues]

Current state: I think we should just add globalsymbols as additional search provider next to ARASAAC and opensymbols.