rclone support from borg2

[Victor239]

The problem

borg2 now supports rclone as a storage provider, so compatibility should be ensured in Vorta.

Requested Solution

Fully compatible rclone support.

Alternatives

N/A

Additional context

N/A

[ThomasWaldmann]

Guess this is relatively easy to solve:

• vorta must be able to deal with borg2's rclone: repo "URLs", they could look like e.g. rclone:mypcloud:somebucket/borgrepo. The string to the right of rclone: must conform to the rclone documentation.
• I think the setup of the remote should be done outside of vorta, just setting up rclone as documented, they have docs for ~100 different providers and we don't need to deal with all that within vorta.