This is a preparatory commit to combine user settings panels into
one. We need to re-register event handlers since they get destroyed
when the settings modal is closed. After re-opening the modal,
clicking the tabs would not do anything unless we re-register our
event handlers.
Some files already were using `noop` in place of `() => {}`.
It's both clearer what it means and is easier to type.
This updates all test files to fully use `noop`, and
adds a shared import from the test lib file.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>