Use separate actions to enable/disable budget phases

This is consistent with the way we use separate actions to hide and
restore records, which is similar to enabling and disabling a record. We
might do something similar with the `toggle_selection` actions in the
future. For now, we're only doing it with budget phases because we're
going to add a similar switch control to hide and restore tenants.

We're also making these actions idempotent, so sending many requests to
the same action will get the same result, which wasn't the case with the
`toggle` action. Although it's a low probability case, the `toggle`
action could result in disabling a phase when trying to enable it if
someone else has enabled it between the time the page loaded and the
time the admin clicked on the "enable" button.

app/controllers/concerns/admin/budget_phases_actions.rb

@@ -6,7 +6,7 @@ module Admin::BudgetPhasesActions
     include ImageAttributes
 
     before_action :load_budget
-    before_action :load_phase, only: [:edit, :update, :toggle_enabled]
+    before_action :load_phase, only: [:edit, :update, :enable, :disable]
   end
 
   def edit
@@ -20,12 +20,21 @@ module Admin::BudgetPhasesActions
     end
   end
 
-  def toggle_enabled
-    @phase.update!(enabled: !@phase.enabled)
+  def enable
+    @phase.update!(enabled: true)
 
     respond_to do |format|
       format.html { redirect_to phases_index, notice: t("flash.actions.save_changes.notice") }
-      format.js
+      format.js { render template: "admin/budgets_wizard/phases/toggle_enabled" }
+    end
+  end
+
+  def disable
+    @phase.update!(enabled: false)
+
+    respond_to do |format|
+      format.html { redirect_to phases_index, notice: t("flash.actions.save_changes.notice") }
+      format.js { render template: "admin/budgets_wizard/phases/toggle_enabled" }
     end
   end