List build problems in staging project page

List the build problems in the following format:

PACKAGE_NAME: STATUS1(ARCH1, ARCH2,...) STATUS2(ARCH3,..) ...

openQA problems are not included.

Co-authored-by: Ana María Martínez Gómez <ammartinez@suse.de>

src/api/app/assets/stylesheets/webui2/staging-workflow.scss

@@ -14,3 +14,7 @@
   }
 }
 
+ul .table-list-group-item {
+  padding: 0.5rem 0.75rem;
+  background-color: transparent;
+}

src/api/app/models/staging/staging_project.rb

@@ -59,8 +59,22 @@ def overall_state
       @overall_state ||= state
     end
 
+    def problems
+      @problems ||= cache_problems
+    end
+
     private
 
+    def cache_problems
+      problems = {}
+      broken_packages.each do |package|
+        problems[package[:package]] ||= {}
+        problems[package[:package]][package[:state]] ||= []
+        problems[package[:package]][package[:state]] << { repository: package[:repository], arch: package[:arch] }
+      end
+      problems.sort
+    end
+
     def state
       return :empty unless staged_requests.exists?
       return :unacceptable if untracked_requests.present? || staged_requests.obsolete.present?

src/api/app/views/webui2/webui/staging/workflows/_problems.html.haml

@@ -1 +1,22 @@
-Placeholder for the content
+- if project.problems.empty?
+  .text-center
+    %i.fas.fa-check-circle.fa-2x.text-success
+- else
+  %ul.list-group.list-group-flush
+    - project.problems.each do |name, states|
+      %li.list-group-item.table-list-group-item
+        = link_to("#{name}:", package_show_path(package: name, project: project))
+        - states.each do |state, values|
+          = state
+          = surround '(', ')' do
+            - values.each do |value|
+              - coma = ', ' unless values.last == value
+              = succeed coma do
+                - if state == 'unresolvable'
+                  = value[:arch]
+                - else
+                  = link_to(value[:arch], package_live_build_log_path(package: name,
+                                                                      repository: value[:repository],
+                                                                      project: project,
+                                                                      arch: value[:arch]))
+