lvconvert: support linear <-> striped convenience conversions

lvconvert: support linear <-> striped convenience conversions

"lvconvert --type {linear|striped|raid*} ..." on a striped/linear
LV provides convenience interim type to convert to the requested
final layout similar to the given raid* <-> raid* conveninece types.

Whilst on it, add missing raid5_n convenince type from raid5* to raid10.

Resolves: rhbz1439925
Resolves: rhbz1447809
Resolves: rhbz1573255