feature: Improve mending building

[evgeny-k]

nowadays it is pain to search required item in mending building so it should be improved.

inherit SK_Mending.ITab_Mending_Building from StorageSearch.ITab_Storage_Enhanced or just use StorageSearch.ITab_Storage_Enhanced.
as a result StorageSearch and load/save store features will be added and 'items' tab will work similar to one in NanoScanner building

[skyarkhangel]

"Mending" would be fully rework soon.