Use lazy loading for config and update to nextcloud 33

[lukasdotcom]

This does the following:

• adds support for nextcloud 33
• Uses userconfig and appconfig when possible with lazy loading
• Also uses sensitive parameter instead of encrypting and decrypting in the app for appconfig (client_id and client_secret)
• Also I noticed that there was code from Fix: Improve sanitization of folder and file names #209 in here for nextcloud versions before 32 and as those versions were dropped for Allow cancelling already running job #286 that portion of code can be removed safely.

[marcelklehr]

woff, big PR. looks good 👍