The post time to chat feature should have a customisable string

[DC23]

Is your feature request related to a problem? Please describe.
At present, the time-of-day chat messages always show the time in a fixed format.

Describe the solution you'd like
The time chat messages should allow the string to be customised. A dialog would allow a template string to be input. A button would show a preview of the formatted chat message or would indicate if there were errors.

Describe alternatives you've considered
A workaround is to use the time change macro functionality with a macro that detects the change in time and formats the string however the user requires. A sample macro for this will be included in release v1.0.0