Move content blocks forms partials to components

This way we can simplify the controller a little bit, and it'll be
easier to write tests for them when we change the code.

app/components/admin/site_customization/content_blocks/form_content_block_component.html.erb

@@ -0,0 +1,19 @@
+<%= form_for [:admin, content_block], html: { class: "edit_page" } do |f| %>
+
+  <%= render "shared/errors", resource: content_block %>
+
+  <div class="small-12 medium-6 column">
+    <%= f.select :name, options_for_select(valid_blocks, selected_content_block) %>
+  </div>
+  <div class="small-12 medium-6 column">
+    <%= f.select :locale, I18n.available_locales %>
+  </div>
+
+  <div class="small-12 column">
+    <%= f.text_area :body, rows: 10 %>
+    <div class="small-12 medium-6 large-3">
+      <%= f.submit class: "button success expanded" %>
+    </div>
+  </div>
+
+<% end %>

app/components/admin/site_customization/content_blocks/form_content_block_component.rb

@@ -0,0 +1,14 @@
+class Admin::SiteCustomization::ContentBlocks::FormContentBlockComponent < ApplicationComponent
+  attr_reader :content_block
+  use_helpers :valid_blocks
+
+  def initialize(content_block)
+    @content_block = content_block
+  end
+
+  private
+
+    def selected_content_block
+      content_block.name
+    end
+end

app/components/admin/site_customization/content_blocks/form_heading_content_block_component.html.erb

@@ -0,0 +1,19 @@
+<%= form_tag(admin_site_customization_update_heading_content_block_path(content_block.id), method: "put") do %>
+  <%= render "shared/errors", resource: content_block %>
+
+  <div class="small-12 medium-6 column">
+    <%= label_tag :name %>
+    <%= select_tag :name, options_for_select(valid_blocks, selected_content_block) %>
+  </div>
+  <div class="small-12 medium-6 column">
+    <%= label_tag :locale %>
+    <%= select_tag :locale, options_for_select(I18n.available_locales, content_block.locale.to_sym) %>
+  </div>
+  <div class="small-12 column">
+    <%= label_tag :body %>
+    <%= text_area_tag :body, content_block.body, rows: 10 %>
+    <div class="small-12 medium-6 large-3">
+      <%= button_tag t("admin.menu.site_customization.buttons.content_block.update"), class: "button success expanded" %>
+    </div>
+  </div>
+<% end %>

app/components/admin/site_customization/content_blocks/form_heading_content_block_component.rb

@@ -0,0 +1,14 @@
+class Admin::SiteCustomization::ContentBlocks::FormHeadingContentBlockComponent < ApplicationComponent
+  attr_reader :content_block
+  use_helpers :valid_blocks
+
+  def initialize(content_block)
+    @content_block = content_block
+  end
+
+  private
+
+    def selected_content_block
+      "hcb_#{content_block.heading_id}"
+    end
+end