feat: add job to remove stale contacts and contact_inboxes (#11186)

- Add a job to remove stale contacts and contact_inboxes across all accounts

Stale anonymous contact is defined as 
- have no identification (email, phone_number, and identifier are NULL)
- have no conversations
- are older than 30 days

---------

Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: Shivam Mishra <scm.mymail@gmail.com>

spec/services/internal/remove_stale_contacts_service_spec.rb

@@ -0,0 +1,41 @@
+require 'rails_helper'
+
+RSpec.describe Internal::RemoveStaleContactsService do
+  describe '#perform' do
+    let(:account) { create(:account) }
+
+    it 'does not delete contacts with conversations' do
+      # Contact with NULL values and conversation
+      contact1 = create(:contact, account: account, email: nil, phone_number: nil, identifier: nil, created_at: 31.days.ago)
+      create(:conversation, contact: contact1)
+
+      # Contact with empty strings and conversation
+      contact2 = create(:contact, account: account, email: '', phone_number: '', identifier: '', created_at: 31.days.ago)
+      create(:conversation, contact: contact2)
+
+      service = described_class.new(account: account)
+      expect { service.perform }.not_to change(Contact, :count)
+    end
+
+    it 'does not delete contacts with identification' do
+      create(:contact, :with_email, account: account, phone_number: '', identifier: nil, created_at: 31.days.ago)
+      create(:contact, :with_phone_number, account: account, email: nil, identifier: '', created_at: 31.days.ago)
+      create(:contact, account: account, identifier: 'test123', created_at: 31.days.ago)
+
+      create(:contact, :with_email, account: account, phone_number: '', identifier: nil, created_at: 31.days.ago)
+      create(:contact, :with_phone_number, account: account, email: nil, identifier: nil, created_at: 31.days.ago)
+      create(:contact, account: account, email: '', phone_number: nil, identifier: 'test1234', created_at: 31.days.ago)
+
+      service = described_class.new(account: account)
+      expect { service.perform }.not_to change(Contact, :count)
+    end
+
+    it 'deletes stale contacts' do
+      create(:contact, account: account, created_at: 31.days.ago)
+      create(:contact, account: account, created_at: 1.day.ago)
+
+      service = described_class.new(account: account)
+      expect { service.perform }.to change(Contact, :count).by(-1)
+    end
+  end
+end