feat: Ability to delete account for administrators (#1874)

## Description

Add account delete option in the user account settings.

Fixes #1555 

## Type of change

- [ ] New feature (non-breaking change which adds functionality)


![image](https://user-images.githubusercontent.com/40784971/110349673-edcc5200-8058-11eb-8ded-a31d15aa0759.png)

![image](https://user-images.githubusercontent.com/40784971/110349778-0c324d80-8059-11eb-9291-abfbffedde5e.png)


## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my own code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>
Co-authored-by: Sojan Jose <sojan.official@gmail.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

spec/mailers/administrator_notifications/integrations_notification_mailer_spec.rb

@@ -0,0 +1,41 @@
+require 'rails_helper'
+require Rails.root.join 'spec/mailers/administrator_notifications/shared/smtp_config_shared.rb'
+
+RSpec.describe AdministratorNotifications::IntegrationsNotificationMailer do
+  include_context 'with smtp config'
+
+  let!(:account) { create(:account) }
+  let!(:administrator) { create(:user, :administrator, email: 'admin@example.com', account: account) }
+
+  describe 'slack_disconnect' do
+    let(:mail) { described_class.with(account: account).slack_disconnect.deliver_now }
+
+    it 'renders the subject' do
+      expect(mail.subject).to eq('Your Slack integration has expired')
+    end
+
+    it 'renders the receiver email' do
+      expect(mail.to).to eq([administrator.email])
+    end
+
+    it 'includes reconnect instructions in the body' do
+      expect(mail.body.encoded).to include('To continue receiving messages on Slack, please delete the integration and connect your workspace again')
+    end
+  end
+
+  describe 'dialogflow_disconnect' do
+    let(:mail) { described_class.with(account: account).dialogflow_disconnect.deliver_now }
+
+    it 'renders the subject' do
+      expect(mail.subject).to eq('Your Dialogflow integration was disconnected')
+    end
+
+    it 'renders the content' do
+      expect(mail.body.encoded).to include('Your Dialogflow integration was disconnected because of permission issues')
+    end
+
+    it 'renders the receiver email' do
+      expect(mail.to).to eq([administrator.email])
+    end
+  end
+end