feat: Add support for template variables in messages content (#6215)

Fixes: #6078

Co-authored-by: Sojan <sojan@pepalo.com>

spec/models/message_spec.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'rails_helper'
+require Rails.root.join 'spec/models/concerns/liquidable_shared.rb'
 
 RSpec.describe Message, type: :model do
   context 'with validations' do
@@ -9,6 +10,10 @@ RSpec.describe Message, type: :model do
     it { is_expected.to validate_presence_of(:account_id) }
   end
 
+  describe 'concerns' do
+    it_behaves_like 'liqudable'
+  end
+
   describe '#reopen_conversation' do
     let(:conversation) { create(:conversation) }
     let(:message) { build(:message, message_type: :incoming, conversation: conversation) }