Various fixes and improvements (#12878)

* Fix unused role routes being generated

* Remove unused JavaScript code

* Refactor filters code to be DRYer

* Fix `.count == 0` comparisons to `.empty?` in views

* Fix filters in views

app/controllers/admin/accounts_controller.rb

@@ -109,21 +109,7 @@ module Admin
     end
 
     def filter_params
-      params.permit(
-        :local,
-        :remote,
-        :by_domain,
-        :active,
-        :pending,
-        :disabled,
-        :silenced,
-        :suspended,
-        :username,
-        :display_name,
-        :email,
-        :ip,
-        :staff
-      )
+      params.slice(*AccountFilter::KEYS).permit(*AccountFilter::KEYS)
     end
   end
 end

app/controllers/admin/custom_emojis_controller.rb

@@ -48,7 +48,7 @@ module Admin
     end
 
     def filter_params
-      params.slice(:local, :remote, :by_domain, :shortcode, :page).permit(:local, :remote, :by_domain, :shortcode, :page)
+      params.slice(:page, *CustomEmojiFilter::KEYS).permit(:page, *CustomEmojiFilter::KEYS)
     end
 
     def action_from_button

app/controllers/admin/instances_controller.rb

@@ -62,7 +62,7 @@ module Admin
     end
 
     def filter_params
-      params.permit(:limited, :by_domain)
+      params.slice(*InstanceFilter::KEYS).permit(*InstanceFilter::KEYS)
     end
   end
 end

app/controllers/admin/invites_controller.rb

@@ -47,7 +47,7 @@ module Admin
     end
 
     def filter_params
-      params.permit(:available, :expired)
+      params.slice(*InviteFilter::KEYS).permit(*InviteFilter::KEYS)
     end
   end
 end

app/controllers/admin/reports_controller.rb

@@ -52,12 +52,7 @@ module Admin
     end
 
     def filter_params
-      params.permit(
-        :account_id,
-        :resolved,
-        :target_account_id,
-        :by_target_domain
-      )
+      params.slice(*ReportFilter::KEYS).permit(*ReportFilter::KEYS)
     end
 
     def set_report

app/controllers/admin/tags_controller.rb

@@ -73,7 +73,7 @@ module Admin
     end
 
     def filter_params
-      params.slice(:directory, :reviewed, :unreviewed, :pending_review, :page, :popular, :active, :name).permit(:directory, :reviewed, :unreviewed, :pending_review, :page, :popular, :active, :name)
+      params.slice(:page, *TagFilter::KEYS).permit(:page, *TagFilter::KEYS)
     end
 
     def tag_params

app/controllers/relationships_controller.rb

@@ -85,7 +85,7 @@ class RelationshipsController < ApplicationController
   end
 
   def current_params
-    params.slice(:page, :status, :relationship, :by_domain, :activity, :order).permit(:page, :status, :relationship, :by_domain, :activity, :order)
+    params.slice(:page, *RelationshipFilter::KEYS).permit(:page, *RelationshipFilter::KEYS)
   end
 
   def action_from_button