Data Quality metadata

[rob-metalinkage]

revisit the logic of #18 but focussing on the use of standardised Data Quality measures instead of PROV.

Stubs for schemas to test against the ISO 19157 DQ measure register are here https://ogcincubator.github.io/dqm-schemas/

[i2vana]

This could be via using measures from the ISO 19157-3 Data quality measures register for simple evaluation of data quality and document this in a provenance schema (using PROV-O and/or ISO 19115-1 LI_Lineage and ISO 19115-2 LE_Lineage).