Add name attribute to heading content blocks

This way we can simplify the code and don't have to rely on `.try`
statements which are confusing and so we don't allow them in the
`Rails/SafeNavigation` Rubocop rule.

spec/models/budget/content_block_spec.rb

@@ -19,4 +19,18 @@ describe Budget::ContentBlock do
                         heading: heading_content_block_en.heading, locale: "es")
     expect(valid_block).to be_valid
   end
+
+  describe "#name" do
+    it "uses the heading name" do
+      block = Budget::ContentBlock.new(heading: Budget::Heading.new(name: "Central"))
+
+      expect(block.name).to eq "Central"
+    end
+
+    it "returns nil on new records without heading" do
+      block = Budget::ContentBlock.new
+
+      expect(block.name).to be_nil
+    end
+  end
 end