feat: Add manual content item

- Copied over the method from government_frontend.This method memoizes the content item from content store to avoid any subsequent calls to content store via gds_api through Services module.
Audit trail:
https://github.com/alphagov/government-frontend/blob/main/app/presenters/content_item/manual_section.rb#L40

Author: sairamya93

app/models/concerns/manual_parts.rb

@@ -26,6 +26,14 @@ def breadcrumbs
         },
       ]
     end
+
+    def manual_content_item
+      @manual_content_item ||= Services.content_store.content_item(base_path)
+    end
+
+    def parsed_content_item
+      manual_content_item.parsed_content
+    end
   end
 
 private

lib/services.rb

@@ -0,0 +1,13 @@
+require "gds_api/content_store"
+
+module Services
+  def self.content_store
+    @content_store ||= GdsApi::ContentStore.new(
+      Plek.new.find("content-store"),
+      # Disable caching to avoid caching a stale max-age in the cache control
+      # headers, which would cause this app to set the wrong max-age on its
+      # own responses
+      disable_cache: true,
+    )
+  end
+end

spec/models/manual_section_spec.rb

@@ -3,4 +3,5 @@
   it_behaves_like "it can have page title", "manual_section", "what-is-content-design"
   it_behaves_like "it can have document heading", "manual_section", "what-is-content-design"
   it_behaves_like "it can have breadcrumbs", "manual_section", "what-is-content-design"
+  it_behaves_like "it can have manual content item", "manual_section", "what-is-content-design"
 end

spec/support/concerns/manual_parts.rb

@@ -29,3 +29,14 @@
     expect(described_class.new(content_item).breadcrumbs).to eq([{ title: "Back to contents", url: "/guidance/content-design/what-is-content-design" }])
   end
 end
+
+RSpec.shared_examples "it can have manual content item" do |document_type, example_name|
+  let(:content_item) { GovukSchemas::Example.find(document_type, example_name:) }
+
+  it "returns an empty hash when content store returns empty body" do
+    stub_request(:get, "http://content-store.dev.gov.uk/content/guidance/content-design/what-is-content-design")
+.to_return(status: 200, body: "{}", headers: {})
+
+    expect(described_class.new(content_item).parsed_content_item).to eq({})
+  end
+end