Create CI Catalog resolver for a single resource

What does this MR do and why?

Adding a single catalog resource graphQL endpoint. Addressing following issue.

Screenshots or screen recordings

See below.

How to set up and validate locally (command line)

1. Enable feature flags:

Feature.enable(:ci_namespace_catalog_experimental)
Feature.enable(:ci_namespace_catalog)
License.feature_available?(:ci_namespace_catalog) #get license if this is not true.

2. Create a project that belongs to a namespace.
3. Add the current user (id: 1) as owner to the namespace.
4. Create Ci::Catalog::Resource in your console

project = Project.last
resource = Ci::Catalog::Resource.new(project: project)
resource.save!

5. In the console:

current_user = User.find_by_id(1)

query = <<~EOQ
query getCiCatalogResource($id: CiCatalogResourceID!) 
{
  ciCatalogResource(id: $id) {
    id
    description
    name
    icon
  } 
}
EOQ

variables = {"id": "gid://gitlab/Ci::Catalog::Resource/1"}

result = GitlabSchema.execute(query, variables: variables, context: { current_user: current_user })
result.to_h

How to set up and validate locally (graphQL interface)

When user is authorised to see a catalog resource

!

When user is not authorised to see a catalog resource

When requested resource does not exist

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.