[New arch] Stop supporting <10 servers

[davigonz]

We have a bunch of constants to consider specific cases for servers with < 10 versions.

@michaelstingl what about removing them? Removing just a couple could help us a lot for handling ownCloud clients in a proper way, as I detailed in #2635

PRs:

• App: End of support for <10 servers  #2756
• Library: End of support for <10 servers android-library#286

Old PRs, need to pick the commits from there and put them in the new branches

• App: [New arch] Stop supporting <10 servers  #2648
• Library: [New arch] Stop supporting <10 servers android-library#265

[michaelstingl]

@michaelstingl what about removing them?

@davigonz Sure. New iOS app is also oC10+.

Who do we need version mapping at all? Preferred way would be to read the capabilities for a feature from the server?