Update Database examples (#203)

Update examples/dbclient
- Add one simple CRUD example per database (mongo, mysql, oracle, postgres)
- Add separate examples for health, metrics and tracing

Update examples/integrations/cdi/jpa
- Add one example per database (mysql, oracle, postgres, h2)

Update examples/integrations/cdi/datasource
- Move datasource examples under the same folder
- Add one example per database (mysql, oracle, postgres, h2)

All examples have consistent README files and default configuration
- docker run commands that match default configuration
- configuration to skip schema creation
- curl commands to exercise the application

All examples use container-registry.oracle.com

Author: romain-grecourt