Let user to provide a custom Grafana dashboard (json)

Users should be able to provide a custom Grafana dashboard as project resource and this needs to be listed in the generated list.json file so that the Kogito Operator can take care of deploy it.
Aspect to consider:

• define a specific path for those resources
• perform basic validation like metrics name (nice to have)
• defining naming convention to bind a dashboard to a resource and disable in this way the generated one (this is related also to ticket KOGITO-5942)