Allow distribution developers to enable/disable settings in the Settings Addon

[juancho0202]

As a distribution creator, I would like to be able to limit/extend the default settings that are being shown to the user in the Settings Dialog.

Acceptance Criteria:

• There is adefaultSettings property in the Settings Addon, which is an object passed down to the Addon specifying the default value expected from each of the settings.
• If the settings property is not passed down from the distribution creator, the Settings Addon will use a default object which is the same as we have right now:

defaults: Settings = {
  language: 'en',
  theme: 'light',
  mode: 'safe',
  showieds: 'off',
  'IEC 61850-7-2': undefined,
  'IEC 61850-7-3': undefined,
  'IEC 61850-7-4': undefined,
  'IEC 61850-8-1': undefined,
};
``