PseudoMetricNormedZmodules should inherit from MetricType

[Brixfoly]

They both use numDomainType as a base field, both have their distance/norm taking values in this field, and the following lemmas ensures that the axioms for metric spaces holds.

normr_ge0 : forall [R : numDomainType] [V : semiNormedZmodType R] (v : V), 0 <= `|v|
normr0P : forall {R : numDomainType} {V : normedZmodType R} {v : V}, reflect (`|v| = 0) (v == 0)
distrC : forall [R : numDomainType] [V : semiNormedZmodType R] (v w : V), `|v - w| = `|w - v|
distrC : forall [R : numDomainType] [V : semiNormedZmodType R] (v w : V), `|v - w| = `|w - v|