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
To explain the rationale of this change, for example, there is
`get_user_activity_summary` which accepts either a `Collection[UserActivity]`,
where `QuerySet[T]` is not strictly `Sequence[T]` because its slicing behavior
is different from the `Protocol`, making `Collection` necessary.
Similarily, we should have `Iterable[T]` instead of `List[T]` so that
`QuerySet[T]` will also be an acceptable subtype, or `Sequence[T]` when we
also expect it to be indexed.
Signed-off-by: Zixuan James Li <p359101898@gmail.com>