feat: Added the ability to create Instagram channel (#11182)

This PR is part of https://github.com/chatwoot/chatwoot/pull/11054 to
make the review cycle easier.

spec/controllers/api/v1/accounts/instagram/authorizations_controller_spec.rb

@@ -0,0 +1,54 @@
+require 'rails_helper'
+
+RSpec.describe 'Instagram Authorization API', type: :request do
+  let(:account) { create(:account) }
+
+  describe 'POST /api/v1/accounts/{account.id}/instagram/authorization' do
+    context 'when it is an unauthenticated user' do
+      it 'returns unauthorized' do
+        post "/api/v1/accounts/#{account.id}/instagram/authorization"
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when it is an authenticated user' do
+      let(:agent) { create(:user, account: account, role: :agent) }
+      let(:administrator) { create(:user, account: account, role: :administrator) }
+
+      it 'returns unauthorized for agent' do
+        post "/api/v1/accounts/#{account.id}/instagram/authorization",
+             headers: agent.create_new_auth_token,
+             as: :json
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+
+      it 'creates a new authorization and returns the redirect url' do
+        post "/api/v1/accounts/#{account.id}/instagram/authorization",
+             headers: administrator.create_new_auth_token,
+             as: :json
+
+        expect(response).to have_http_status(:success)
+        expect(response.parsed_body['success']).to be true
+
+        instagram_service = Class.new do
+          extend InstagramConcern
+          extend Instagram::IntegrationHelper
+        end
+        frontend_url = ENV.fetch('FRONTEND_URL', 'http://localhost:3000')
+        response_url = instagram_service.instagram_client.auth_code.authorize_url(
+          {
+            redirect_uri: "#{frontend_url}/instagram/callback",
+            scope: Instagram::IntegrationHelper::REQUIRED_SCOPES.join(','),
+            enable_fb_login: '0',
+            force_authentication: '1',
+            response_type: 'code',
+            state: instagram_service.generate_instagram_token(account.id)
+          }
+        )
+        expect(response.parsed_body['url']).to eq response_url
+      end
+    end
+  end
+end