Remove duplication in timeline component

This way adding new steps will be easier.

app/components/admin/budgets_wizard/creation_timeline_component.html.erb

@@ -1,8 +1,7 @@
 <ol class="creation-timeline">
-  <li <%= "aria-current='step'" unless step_groups? %>>
-    <%= t("admin.budgets_wizard.creation_timeline.budget") %>
-  </li>
-  <li <%= "aria-current='step'" if step_groups? %>>
-    <%= t("admin.budgets_wizard.creation_timeline.groups") %>
+  <% steps.each do |step| %>
+    <li <%= "aria-current='step'" if step == current_step %>>
+      <%= t("admin.budgets_wizard.creation_timeline.#{step}") %>
     </li>
+  <% end %>
 </ol>

app/components/admin/budgets_wizard/creation_timeline_component.rb

@@ -1,13 +1,13 @@
 class Admin::BudgetsWizard::CreationTimelineComponent < ApplicationComponent
-  attr_reader :step
+  attr_reader :current_step
 
-  def initialize(step)
-    @step = step
+  def initialize(current_step)
+    @current_step = current_step
   end
 
   private
 
-    def step_groups?
-      step == "groups"
+    def steps
+      %w[budget groups]
     end
 end