Rename: VG --> StoragePool; LogicalVolume to LocalVolume

[liyimeng]

Ⅰ. Issue Description

The project named, open-local, not open-lvm, it is suppose to support or local storage solution more than LVM.

Consider to refact the code to make it more generic and prepare to accept new local storage type.

This seem to be a big jobs, especially some of this naming is used in yaml file, which likely break backward compatibility.

Not sure if this is feasible.

[TheBeatles1994]

We are refactoring the codes now to support more local storage types by implementing the scheduling framework plugin, which is expected to be achieved by September.

[liyimeng]

Thanks for the update! @TheBeatles1994