Update the UI to switch user aka become user

[theskumar]

Fixes #4131

• Rename to "switch user"
• Can switch from the user menu
• Switch to choices.js from Select2
• Update the hijacked view, shows an alert at the top

[frjo]

This looks and works really nicely! Will be a pleasure to use when we get it deployed.

I have one issue. The function get_become_user_choices() is slow. I think get_role_names() takes up most of the time.

With 4000 users it takes around three (3) seconds. I think OTF has even more users. This should not be used in production but even test data can have a lot of users.

Possible to speed it up a bit, showing the role in the list is useful so good if we can keep that. Maybe caching the list would work?

[theskumar]

I have one issue. The function get_become_user_choices() is slow. I think get_role_names() takes up most of the time.

With 4000 users it takes around three (3) seconds. I think OTF has even more users. This should not be used in production but even test data can have a lot of users.

Will look into it.

[wes-otf]

This is super slick! I really like the banner as opposed to the pop up window that you need to dismiss every time you reload the page. Nice improvement!

[theskumar]

@frjo Updated the query to fetch the groups. It should always come down to 2 queries now. That said, if we face issue in the test site, we can switch to fetching the options as you type, via a search api.

[theskumar]

The new implementation of user.is_* checks will improve the performance overall at multiple places.

[frjo]

Now the load time is more or less instant and works equally well in other respects.