chore: Provider API prototype (#3112)

Enabling Support for Whatsapp via 360Dialog as a prototype for the provider APIs. 

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>

spec/services/whatsapp/incoming_message_service_spec.rb

@@ -0,0 +1,21 @@
+require 'rails_helper'
+
+describe Whatsapp::IncomingMessageService do
+  let!(:whatsapp_channel) { create(:channel_whatsapp) }
+
+  describe '#perform' do
+    context 'when valid text message params' do
+      it 'creates appropriate conversations, message and contacts' do
+        params = {
+          'contacts' => [{ 'profile' => { 'name' => 'Sojan Jose' }, 'wa_id' => '2423423243' }],
+          'messages' => [{ 'from' => '2423423243', 'id' => 'SDFADSf23sfasdafasdfa', 'text' => { 'body' => 'Test' },
+                           'timestamp' => '1633034394', 'type' => 'text' }]
+        }.with_indifferent_access
+        described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
+        expect(whatsapp_channel.inbox.conversations.count).not_to eq(0)
+        expect(Contact.all.first.name).to eq('Sojan Jose')
+        expect(whatsapp_channel.inbox.messages.first.content).to eq('Test')
+      end
+    end
+  end
+end