Add `sync_percent` for `lvm_vol_group` produced by `inputs.lvm`

[niklasf]

Use Case

By default, lvs provides a Cpy%Sync column to monitor the progress of copies (copy_percent) and raid scrubbing or repair (sync_percent).

This is useful to monitor as important status information regarding the health and performance of a logical volume.

Expected behavior

inputs.lvm plugin provides sync_percent as an additional field on lvm_vol_group.

Actual behavior

Field not yet provided.

Additional info

No response