Create values schemas for all VS services

All VS services should have an up-to-date schema of the values

• It would allow easier documentation (schema is a base and additional reference text added only if necessary)
• Validation would happen via helm automatically before starting a deployment

Following services have a values config schema:

• client

Following packages have a service config schema but not extended to a values schema:

• harvester
• preprocessor-v3

Following services are missing a config schema completely:

• scheduler
• core (productTypes,browseTypes and so on)
• vs-common (its models should have a schema, because they are directly imported in preprocessor-v3 and harvester)
• cache
• seeder
• postgresql - reference external?