Change Forums setting in Profile settings need from legacy forums to Vanilla

[Oanh-and-only-Oanh]

Describe bug:
When user clicks on Forums Settings in Profile settings here https://www.topcoder.com/settings/preferences, user is taken to legacy forums settings here https://apps.topcoder.com/forums/?module=Settings

Expected behavior:
IDEALLY, When user clicks on Forums Settings, the vanilla Forums settings page should be imbedded into Community App. It should NOT take the user to a separate page to manage their forums notification preferences. You can check with @jmgasper for help. See design below:

If embedding is not an option (too difficult), then when user clicks on Forums Settings, a new window opens to https://discussions.topcoder.com/profile/preferences

[luizrrodrigues]

Duplicate of #5433