chore: Clean up report & knowledge base policies (#11234)

- Removes the portal_members table and all associated records
- Updates policies to use custom roles with knowledge_base_manage
permission
- Updates controllers, models, and views to work without portal
membership
- Adds tests for the new permission model

spec/enterprise/policies/article_policy_spec.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Enterprise::ArticlePolicy', type: :policy do
+  subject(:article_policy) { ArticlePolicy }
+
+  let(:account) { create(:account) }
+  let(:agent) { create(:user, account: account) } # Needed for author
+  let(:portal) { create(:portal, account: account) }
+  let(:article) { create(:article, account: account, portal: portal, author: agent) }
+
+  # Create a custom role with knowledge_base_manage permission
+  let(:custom_role) { create(:custom_role, account: account, permissions: ['knowledge_base_manage']) }
+  let(:agent_with_role) { create(:user) } # Create without account
+  let(:agent_with_role_account_user) do
+    create(:account_user, user: agent_with_role, account: account, role: :agent, custom_role: custom_role)
+  end
+  let(:agent_with_role_context) do
+    { user: agent_with_role, account: account, account_user: agent_with_role_account_user }
+  end
+
+  permissions :index?, :update?, :show?, :edit?, :create?, :destroy?, :reorder? do
+    context 'when agent with knowledge_base_manage permission' do
+      it { expect(article_policy).to permit(agent_with_role_context, article) }
+    end
+  end
+end