feat: add support for mount options

[leafty]

Manually tested: https://renku-ci-ds-741.dev.renku.ch/

1. Start a v2 session with at least one data connector
2. Find and edit one of the k8s secrets used to mount a remote

   data:
     configData: ...configData...
     remote: ...remote...
     remotePath: ...remotePath...
     vfsOpt: eyJDYWNoZU1vZGUiOiAiZnVsbCJ9Cg== # {"CacheMode": "full"}
     mountOpt: eyJBdHRyVGltZW91dCI6IDYwMDAwMDAwMDAwfQo= # {"AttrTimeout": 60000000000}

3. Delete the session pod and wait, the session should be brought up again with the right parameters now...
   Logs:

   I0409 08:25:43.708804       1 rclone.go:155] executing create config command name=rclone-mounter-pvc-813b3d05-2db2-4673-9555-a1f6d37336f4, storageType=doi
   I0409 08:25:43.855833       1 rclone.go:169] created config: rclone-mounter-pvc-813b3d05-2db2-4673-9555-a1f6d37336f4
   I0409 08:25:43.856248       1 rclone.go:215] executing mount command args={"fs":"rclone-mounter-pvc-813b3d05-2db2-4673-9555-a1f6d37336f4:/","mountPoint":"/var/lib/kubelet/pods/be815582-f5ac-455b-8d24-2643d7c7ec85/volumes/kubernetes.io~csi/pvc-813b3d05-2db2-4673-9555-a1f6d37336f4/mount","vfsOpt":{"ReadOnly":true,"DirCacheTime":60000000000,"CacheMode":"full"},"mountOpt":{"AllowNonEmpty":true,"AllowOther":true,"AttrTimeout":60000000000}}