feat: Conversation workflow backend changes (#13070)

Extracted the backend changes from
https://github.com/chatwoot/chatwoot/pull/13040

- Added the support for saving `conversation_required_attributes` in
account
- Delete `conversation_required_attributes` if custom attribute deleted.

Co-authored-by: Vinay Keerthi <11478411+stonecharioteer@users.noreply.github.com>

spec/models/custom_attribute_definition_spec.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe CustomAttributeDefinition do
+  describe 'callbacks' do
+    describe '#cleanup_conversation_required_attributes' do
+      let(:account) { create(:account) }
+      let(:attribute_key) { 'test_attribute' }
+      let!(:custom_attribute) do
+        create(:custom_attribute_definition,
+               account: account,
+               attribute_key: attribute_key,
+               attribute_model: 'conversation_attribute')
+      end
+
+      context 'when conversation attribute is in required attributes list' do
+        before do
+          account.update!(conversation_required_attributes: [attribute_key, 'other_attribute'])
+        end
+
+        it 'removes the attribute from conversation_required_attributes when destroyed' do
+          expect { custom_attribute.destroy! }
+            .to change { account.reload.conversation_required_attributes }
+            .from([attribute_key, 'other_attribute'])
+            .to(['other_attribute'])
+        end
+      end
+
+      context 'when attribute is contact_attribute' do
+        let!(:contact_attribute) do
+          create(:custom_attribute_definition,
+                 account: account,
+                 attribute_key: attribute_key,
+                 attribute_model: 'contact_attribute')
+        end
+
+        before do
+          account.update!(conversation_required_attributes: [attribute_key])
+        end
+
+        it 'does not modify conversation_required_attributes when destroyed' do
+          expect { contact_attribute.destroy! }
+            .not_to(change { account.reload.conversation_required_attributes })
+        end
+      end
+    end
+  end
+end