To allow `custom_profile_field` to display in user profile popover,
added new boolean field "display_in_profile_summary" in its model class.
In `custom_profile_fields.py`, functions are edited as per conditions,
like currently we can display max 2 `custom_profile_fields` except
`LONG_TEXT` and `USER` type fields.
Default external account custom profile fields made updatable for only
this new field, as previous they were not updatable.
Fixes part of: #21215
