feat: Line Channel (#2904)

- Ability to configure line bots as a channel in chatwoot
- Receive a message sent to the line bot in chatwoot
- Ability to reply to line users from chatwoot

fixes: #2738

spec/services/line/send_on_line_service_spec.rb

@@ -0,0 +1,18 @@
+require 'rails_helper'
+
+describe Line::SendOnLineService do
+  describe '#perform' do
+    context 'when a valid message' do
+      it 'calls @channel.client.push_message' do
+        line_client = double
+        line_channel = create(:channel_line)
+        message = create(:message, message_type: :outgoing, content: 'test',
+                                   conversation: create(:conversation, inbox: line_channel.inbox))
+        allow(line_client).to receive(:push_message)
+        allow(Line::Bot::Client).to receive(:new).and_return(line_client)
+        expect(line_client).to receive(:push_message)
+        described_class.new(message: message).perform
+      end
+    end
+  end
+end