Reset the entire exam to allow another attempt.
The number of attempts and how often the retry option is available can be defined in
the tutorialExtras_setup() function.
The tutorial must be available in a package for this button to work as the function requires
a name and package specification.
Shiny ui and server logic for the lock computation.
Note that when including these functions in a learnr Rmd document it is necessary that
the server function, reset_server(), be included in an R chunk where context="server" as
they interact with the underlying Shiny functionality. Conversely, the ui function,
reset_button_ui(), must not be included in an R chunk with a context.