FR: Add possibility to change settings of Restic

[nucleusv]

Hello,

would be great to have possibility to change settings of Restic like this:

The number of concurrent connections to the Azure Blob Storage service can be set with the -o azure.connections=10. By default, at most five parallel connections are established.
https://restic.readthedocs.io/en/stable/030_preparing_a_new_repo.html#microsoft-azure-blob-storage

[tamalsaha]

I agree. We should do this.

[tamalsaha]

• Add MaxConnections int json:"maxConnections,omitempty"`` to https://github.com/kmodules/objectstore-api/blob/master/api/v1/types.go for Azure, GCS, B2.