Allow jumping in user management list in portal

**Problem**
Right now, jumping to a specific list after removing a user require me clicking the largest page (4 -> 7 -> ...) until the desired page is available in the number.

Should allow typing a page number to jump to that page instead.

Should show the current page in url query param and allow changing the query param in url to jump to that page.

**Appetite**
1 week?

**Solution**
As in description. No UI proposal here, up to designer/PM.

**Rabbit holes**
N/A

**No-goes**
N/A

Locate the portal's user-management list and inspect how pagination and URL query parameters are currently handled. Define the page-number input or control with the designer or PM, then verify that removing users, typing a page, and editing the query parameter all reach the expected page.

Written by the indexing model from the issue text.