[webui][api] Show kiwi packages list

Add packages list for the package groups with `image` type and
`onlyRequired` pattern type to the Kiwi::Image show page.

Mob-programmed by @mdeniz, @DavidKang and @Ana06.

src/api/app/assets/stylesheets/webui/application/kiwi_image.scss

@@ -48,3 +48,7 @@
 #kiwi_repository_update_form_save {
   margin-left: 1em;
 }
+
+.kiwi_packages_table {
+  width: 98%
+}

src/api/app/models/kiwi/image.rb

@@ -22,7 +22,9 @@ class Kiwi::Image < ApplicationRecord
   #### Associations macros (Belongs to, Has one, Has many)
   has_one :package, foreign_key: 'kiwi_image_id', class_name: '::Package', dependent: :nullify, inverse_of: :kiwi_image
   has_many :repositories, -> { order(order: :asc) }, dependent: :destroy, index_errors: true
-  has_many :package_groups, dependent: :destroy, index_errors: true
+  has_many :package_groups, -> { order(:id) }, dependent: :destroy, index_errors: true
+  has_many :kiwi_packages, -> { where(kiwi_package_groups: { kiwi_type: Kiwi::PackageGroup.kiwi_types[:image], pattern_type: 'onlyRequired' }) },
+           through: :package_groups, source: :packages
 
   #### Callbacks macros: before_save, after_save, etc.
 

src/api/app/views/webui/kiwi/images/show.html.haml

@@ -10,3 +10,11 @@
     - @image.repositories.each do |repository|
       = render partial: 'repository_entry', locals: {repository: repository}
     = button_to('Edit', edit_kiwi_image_path(@image), method: :get)
+
+%h3 Packages
+- if @image.kiwi_packages.empty?
+  %p There are no packages.
+- else
+  %p
+    %strong
+      = @image.kiwi_packages.pluck(:name).join(', ')