[Feature] LEXIS Datatypes

Define following data types in jsonschema syntax to be used in Airflow dags as schema for Param. Should be the same according TOSCA YAML specification in yaml2dag
- lexis.datatypes.ddi.Metadata
- lexis.datatypes.ddi.FileSource
- lexis.datatypes.ddi.DatasetSource
- lexis.datatypes.ddi.DatasetDestination
- lexis.datatypes.heappe.ComputationResource

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information