* fixed #26887

* fix identation

There is a setup check that prevents installing on Windows.
No need to keep the old unsupported Windows code paths.

Also fix the posix test that was running the wrong verify method:

* Copyright is with ownCloud GmbH now

* Recreate all license headers

Some auth mechanisms like SessionCredentials need to register hooks
early, so they cannot be lazy loaded.

Probably nice for the people that contributed to 9.0 to see themselves in the AUTHORS file :)

Stores user credentials in the database after user login, uses the new
CredentialsManager class

The SFTP backend now supports public key authentication alongside
password authentication.

SMB_OC has been merged with SMB, via the identifier aliases mechanism.
Legacy migration is done to the Session Credentials password mechanism

The Rackspace/OpenStack differences have been split into separate auth
mechanisms, with correct legacy migration

Introduces the basic password authentication mechanism, along with a
mechanism based on ownCloud credentials stored in the user session.

Change to lib/private is an extension of PermissionsMask, as
isSharable() override was missing.

Session credentials auth mechanism now disables sharing on applied
storages, as credentials will not be available.

The following functions have been removed:
 - addMountPoint()
 - removeMountPoint()
 - movePersonalMountPoint()

registerBackend() has been rewritten as a shim around BackendService,
allowing legacy code to interact with the new API seamlessly

addMountPoint() was already disconnected from all production code, so
this commit completes the job and removes the function itself, along
with disconnecting and removing related functions. Unit tests have
likewise been removed.

getAbsoluteMountPoints(), getSystemMountPoints() and
getPersonalMountPoints() have been rewritten to use the StoragesServices