feat: autogenerate vapid keys for push notifications (#3128)

* feat: Autogenerate push notification keys
* add vapid service class and remove pushkey model
* add spec for vapid service
* unset vapid env keys
* Unset VAPID_PRIVATE_KEY env variable

Co-authored-by: Sojan Jose <sojan@chatwoot.com>
Co-authored-by: Vishnu Narayanan <vishnu@chatwoot.com>

lib/vapid_service.rb

@@ -0,0 +1,25 @@
+class VapidService
+  def self.public_key
+    vapid_keys['public_key']
+  end
+
+  def self.private_key
+    vapid_keys['private_key']
+  end
+
+  def self.vapid_keys
+    config = GlobalConfig.get('VAPID_KEYS')
+    return config['VAPID_KEYS'] if config['VAPID_KEYS'].present?
+
+    # keys don't exist in the database. so let's generate and save them
+    keys = Webpush.generate_key
+    # TODO: remove the logic on environment variables when we completely deprecate
+    public_key = ENV['VAPID_PUBLIC_KEY'] || keys.public_key
+    private_key = ENV['VAPID_PRIVATE_KEY'] || keys.private_key
+
+    i = InstallationConfig.where(name: 'VAPID_KEYS').first_or_create(value: { public_key: public_key, private_key: private_key })
+    i.value
+  end
+
+  private_class_method :vapid_keys
+end