[CG] Add VTs for v[567]i1 and v[567]f16 (#151763)

[recommit after fixing #152150]

We already had corresponding f32 and i32 vector types for these sizes.

Also add VTs v[567]i8 and v[567]i16:  these are needed by the Hexagon
backend which for each i1 vector types want to query information about
the corresponding i8 and i16 types in
HexagonTargetLowering::getPreferredHvxVectorAction.

Author: anemet