Decide how to unblock migration of "Edit user profile" dialog

Steps to reproduce an issue:
1) deploy demo webapp with https://git.magnolia-cms.com/projects/PLATFORM/repos/ui/pull-requests/1624/overview
2) login as some demo user (not superuser, e.g. tina, peter, eric)
3) try to access "Edit user profile" dialog

Expected:

• dialog opens and works fine

Actual:

• red bar appears, dialog can't be used

Notes (from above linked PR):
there are basically two options here:

1. reconfigure demo user permissions and update MgnlUserManager like here:
   https://git.magnolia-cms.com/projects/MODULES/repos/demo-projects/pull-requests/182/overview
   https://git.magnolia-cms.com/projects/PLATFORM/repos/main/pull-requests/954/overview
2. create custom password field with desired functionality ootb (as in M5) like here:
   https://git.magnolia-cms.com/projects/PLATFORM/repos/ui/pull-requests/1614/overview