chore: Custom Roles to manage permissions [ UI ] (#9865)

In admin settings, this Pr will add the UI for managing custom roles (
ref: https://github.com/chatwoot/chatwoot/pull/9995 ). It also handles
the routing logic changes to accommodate fine-tuned permissions.

---------

Co-authored-by: Pranav <pranavrajs@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

spec/enterprise/controllers/enterprise/api/v1/accounts/agents_controller_spec.rb

@@ -3,10 +3,25 @@ require 'rails_helper'
 RSpec.describe 'Enterprise Agents API', type: :request do
   let(:account) { create(:account) }
   let(:admin) { create(:user, account: account, role: :administrator) }
+  let!(:custom_role) { create(:custom_role, account: account) }
+
+  describe 'POST /api/v1/accounts/{account.id}/agents' do
+    let(:params) { { email: 'test@example.com', name: 'Test User', role: 'agent', custom_role_id: custom_role.id } }
+
+    context 'when it is an authenticated administrator' do
+      it 'creates an agent with the specified custom role' do
+        post "/api/v1/accounts/#{account.id}/agents", headers: admin.create_new_auth_token, params: params, as: :json
+
+        expect(response).to have_http_status(:success)
+        agent = account.agents.last
+        expect(agent.account_users.first.custom_role_id).to eq(custom_role.id)
+        expect(JSON.parse(response.body)['custom_role_id']).to eq(custom_role.id)
+      end
+    end
+  end
 
   describe 'PUT /api/v1/accounts/{account.id}/agents/:id' do
     let(:other_agent) { create(:user, account: account, role: :agent) }
-    let!(:custom_role) { create(:custom_role, account: account) }
 
     context 'when it is an authenticated administrator' do
       it 'modified the custom role of the agent' do