[Advanced Settings] Retrieve settings outside Kibana Settings application component

[ElenaStoeva]

In #209136, we started a discussion that it might be clearer if we retrieve all settings and filter them out based on business logic (e.g. by solution, read-only settings, etc) outside of the Kibana Settings application; that is, the settings can be retrieved in src/platform/plugins/private/advanced_settings/public/plugin.tsx and passed to the KibanaSettingsApplication component. This way, the business logic for determining which settings should be displayed in the app will be separate from the React component.

[elasticmachine]

Pinging @elastic/kibana-management (Team:Kibana Management)