Closes #36

I have:

• decoupled API client from public facade
• decoupled caching from API client
• started implementation of v2 API
• implemented an auto-switch to new API on 1st of October

However I've spent already quite a long time with it so now I put it here so that someone can finish the work. There are TODOs in AresV2 class - basically 3 of 4 methods have to be rewritten and the already rewritten method has some BC issues which I'm not able to solve on my own. Maybe @dfridrich can look into that BC issues.

Resources:

• announcement: https://www.mfcr.cz/cs/ministerstvo/informacni-systemy/ares--administrativni-registr-ekonomicky
• API base URL: https://ares.gov.cz/ekonomicke-subjekty-v-be/rest/{registry}/{ico}
• API docs: https://ares.gov.cz/swagger-ui
• API fields docs: https://www.mfcr.cz/assets/cs/media/2023-08-01_ARES-Technicka-dokumentace-Katalog-verejnych-sluzeb.pdf
• related upgrading PR in h4kuna/ares: Support new ARES2 API h4kuna/ares#31
• registries overview: https://ares.gov.cz/stranky/popis
• old API docs: https://wwwinfo.mfcr.cz/ares/ares_xml.html.en