Add 'visible' field for helm registries (deafult: true)

[ayalash]

The new field should be set to true on new helm registry's discovery.
It should also be set to true in the migration of current DB.

This field will be used by the frontend.

Setting this field to false for specific registry by API, should be added as well.

[ayalash]

@popen2 Please assign this issue to me

[ayalash]

The above description is not enough, the visibility should be per env, and not for the whole server.
Suggested solution:

1. Add deployment_kinds table, which monitor exist kinds (by UUID)
2. Add env_to_deployment_kinds table, which describes the relations between env to deployment-kind
3. The UI should only show (for each env) the deployment-kinds that are visible according to the relations table.

[ayalash]

#77 is implementing the first AI from my last comment (creation of deployment_kinds table)

@popen2 about the env_to_deployment_kinds, that only disabled kinds will appear in that table, or a cartesian product of kinds and environments ?