Move create/destroy actions for api/v1/statuses to namespace (#3678)

Each of mute, favourite, reblog has been updated to:

- Have a separate controller with just a create and destroy action
- Preserve historical route names to not break the API
- Mild refactoring to break up long methods

spec/routing/api_routing_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 describe 'API routes' do
@@ -50,6 +52,36 @@ describe 'API routes' do
       expect(get('/api/v1/statuses/123/favourited_by')).
         to route_to('api/v1/statuses/favourited_by_accounts#index', status_id: '123')
     end
+
+    it 'routes reblog' do
+      expect(post('/api/v1/statuses/123/reblog')).
+        to route_to('api/v1/statuses/reblogs#create', status_id: '123')
+    end
+
+    it 'routes unreblog' do
+      expect(post('/api/v1/statuses/123/unreblog')).
+        to route_to('api/v1/statuses/reblogs#destroy', status_id: '123')
+    end
+
+    it 'routes favourite' do
+      expect(post('/api/v1/statuses/123/favourite')).
+        to route_to('api/v1/statuses/favourites#create', status_id: '123')
+    end
+
+    it 'routes unfavourite' do
+      expect(post('/api/v1/statuses/123/unfavourite')).
+        to route_to('api/v1/statuses/favourites#destroy', status_id: '123')
+    end
+
+    it 'routes mute' do
+      expect(post('/api/v1/statuses/123/mute')).
+        to route_to('api/v1/statuses/mutes#create', status_id: '123')
+    end
+
+    it 'routes unmute' do
+      expect(post('/api/v1/statuses/123/unmute')).
+        to route_to('api/v1/statuses/mutes#destroy', status_id: '123')
+    end
   end
 
   describe 'Timeline routes' do