This introduces a function that checks for both the existence and the
expiration of the `selected_send_later_timestamp`.
The logic it supports prevents users from scheduling a message to send
in the past or less than five minutes into the future at the level of
the UI (specifically the popover on the \vdots component of the Send
button). That can happen if a user attempts to edit a previously
scheduled message.
Fixes#25439.
This commit ensures that user-locale and 24-hour preferences are
respected in the message-scheduling modal. It also simplifies the
translation of text strings in the scheduling modal.
Available scheduling options and their time values, including whether
the options are allowed, are now calculated every time a user opens
the scheduling modal.
In order to achieve those things, additional interrelated fixes here
accomplish the following:
1. Modal-scheduling opts now have data- attributes containing
timestamps for the time a message will be scheduled to send.
2. With those timestamps in place, the logic for setting the
scheduled send-time is simplified.
3. There are no more `send_later_xxx` global variables in the
`schedule_send` module.
Fixes#25403.
This commit extracts date-based logic from the popover menu file and
puts it in with the scheduled-messages logic.
The aim is for greater testability, with some initial tests now
presented on the date-based logic.
Tim Abbott
Karl Stolley