Feature: Support file type messages on widget and dashboard (#659)

- Adds support for file upload

Co-authored-by: Pranav Raj Sreepuram <pranavrajs@gmail.com>
Co-authored-by: Sojan <sojan@pepalo.com>

spec/controllers/api/v1/widget/messages_controller_spec.rb

@@ -57,6 +57,7 @@ RSpec.describe '/api/v1/widget/messages', type: :request do
         expect(json_response['content']).to eq(message_params[:content])
 
         expect(conversation.messages.last.attachment.file.present?).to eq(true)
+        expect(conversation.messages.last.attachment.file_type).to eq('image')
       end
     end
   end