Add a view password functionality on login

[cielf]

Summary

Add the "eyeball" functionality on the login page so someone can check their password is spelled correctly.

Why?

Just a nice touch so people can confirm they are typing their password correctly if they are having trouble logging in.

Details

Users can view their password, using the "eyeball" functionality. This is not turned on by default, of course.

This is probably a good first issue for a front-end person.

Criteria for completion

• behaviour as described
• tests to confirm behaviour.

[inane-pixel]

I can do this one!

[cielf]

We mostly have new people work on one thing at a time, to spread around the good first issues -- do you want this or the alignment one as your first?