aliases/implications: remove dead approving/updating code.

Remove the edit, update, and approve endpoints for tag aliases and
implications. These have been useless since individual alias and
implication requests were removed. Aliases and implications could only
be edited or approved if they were in the pending state, which is no
longer possible.

Also remove unused new alias/implication request forms.

config/routes.rb

@@ -241,16 +241,8 @@ Rails.application.routes.draw do
       get :autocomplete
     end
   end
-  resources :tag_aliases do
-    member do
-      post :approve
-    end
-  end
-  resources :tag_implications do
-    member do
-      post :approve
-    end
-  end
+  resources :tag_aliases, only: [:show, :index, :destroy]
+  resources :tag_implications, only: [:show, :index, :destroy]
   resources :uploads do
     collection do
       post :preprocess