This commit adds "(guest)" indicator to user names of guests
in mention pill if the enable_guest_user_indicator setting is
enabled for the organization. Note that the actual message
content does not include the indicator.
`copy code` button now show a `Copied!` tooltip when clicked.
It implements a similar function used on `saved as draft` notice.
We need to modify the copy_code_button template to limit
data-tippy-trigger to not include click; otherwise, repeated clicks to
copy code will incorrectly also display the "Copy code" tooltip
alternating with "Copied".
Fixes part of #21036.
Implemented date localization using native Intl object.
Created special function get_localized_date_or_time_for_format
Made necessary string formatting changes in 'timerender.ts'.
Fixed tests and added some localization tests too.
Tested on my local development server, with some random languages.
Fixes#23987.
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>