toollib: honour '-H|--history' switch while executing process_each_lv_in_vg

toollib: honour '-H|--history' switch while executing process_each_lv_in_vg

When processing LVs in a VG and when the -H|--history switch is used,
make process_each_lv_in_vg to iterate over historical volumes too.

For each historical LV, we use dummy struct logical_volume instance with
the "this_glv" reference set to a wrapper over proper struct
historical_logical_volume representation. This makes it possible to process
historical LVs just like normal live LVs (though a dummy one without any
segments and all the other fields zeroed and blank) and it also allows
for using all historical LV related information via lv->this_glv->historical
reference.

One can use a simple call to lv_is_historical to make a difference between
live and historical LV in all the code that is called by process_each_* fns.