console: add nightly builds

[chrisseto]

This commit configures CI to push nightly builds of the console chart to the console-unstable docker repository to aid in the release of console V3.

Additionally, this commit adds schema generation to the console chart to prevent usage of out of date values files.

[chrisseto]

Waiting on #510 to merge

[RafalKorepta]

First the charts/redpanda needs to bump charts/console go depedency to unreleased v3.0.0 version. gen package rightly shows compilation error, because replace directive removes few fields that console.tpl.go is using. When I tried to fix it I stopped at console values that are null, but schema does not allow it.

Few examples from unit tests

        	Error Trace:	/Users/rafalkorepta/workspace/redpanda/redpanda-operator/charts/console/chart_test.go:88
        	Error:      	Received unexpected error:
        	            	values don't meet the specifications of the schema(s) in the following chart(s):
        	            	console:
        	            	- service.targetPort: Invalid type. Expected: integer, given: null
        	            	- ingress.className: Invalid type. Expected: string, given: null
        	Test:       	TestTemplate/autoscaling-memory

        	Error Trace:	/Users/rafalkorepta/workspace/redpanda/redpanda-operator/charts/console/chart_test.go:88
        	Error:      	Received unexpected error:
        	            	values don't meet the specifications of the schema(s) in the following chart(s):
        	            	console:
        	            	- podSecurityContext.fsGroupChangePolicy: podSecurityContext.fsGroupChangePolicy must be one of the following: "OnRootMismatch", "Always"
        	Test:       	TestTemplate/case-049

I only saw JSONSchemaExtend function on specific type that allows to overwrite mentioned properties:

		schema.Properties.Set(key, &jsonschema.Schema{
			OneOf: []*jsonschema.Schema{
				prop,
				{Type: "null"},
			},
		})

[chrisseto]

I've pulled out the schema changes for now as they carry some additional complications.