Fix double releasing of vg when repairing of vg is requested.

Fix double releasing of vg when repairing of vg is requested.

Several commands calls process_each_vg() and in provided
callback it explicitly recovers VG if inconsistent.
(vgchange, vgconvert, vgscan)

It means that old VG is released and reread  but the function
above (process_one_vg) tries to unlock and release old VG.

Patch moves the repair logic into _process_one_vg() function.

It always tries to read vg (even inconsistent) and then decides
what to do according new defined parameter.

Also patch unifies inconsistent error messages.

The only slight change if for vgremove command, where
it now tries to repair VG before it removes if force arg is given.
(It works similar way before, just the order of operation changed).