Add vBoxxCloud and leitzcloud as a provider

[KaisAhmad]

Hi,

This PR is for adding vBoxxCloud and leitzcloud to the provider list. Both cloud providers use OnlyOffice. I couldn't figure out which branch to send this PR to so if I need to target a different branch I would be happy to hear about it and change it!

Any feedback is always welcome

[CLAassistant]

All committers have signed the CLA.

[ibnpetr]

Your interest in integrating with our product is greatly appreciated.
Currently, there are only a few providers that are included into the build out of the box. (the connectors were created and/or evaluated by our team)
We will discuss adding the above mentioned connectors for the future releases
By following the instructions, you can now add the providers for your installation

[KaisAhmad]

Alright I'm curious what you guys think of vBoxx and leitzcloud! Hope they can be added eventually. We already use them locally, but it would be great if we could also recommend them to our customers as well. If there are any questions I would love to hear them :)

[KaisAhmad]

Your interest in integrating with our product is greatly appreciated. Currently, there are only a few providers that are included into the build out of the box. (the connectors were created and/or evaluated by our team) We will discuss adding the above mentioned connectors for the future releases By following the instructions, you can now add the providers for your installation

@ibnpetr had you managed to look with the team into the possibility of adding vBoxxCloud and leitzcloud? There are no build instructions available yet for Windows and Mac. Having customers manually add providers is unfortunately difficult to impossible.

[vBoxx]

vBoxx would like this live.