View current grade and submission attempt on all question and exercises for a user.
This is used so users can check their progress when working on a tutorial
that allows for multiple attempts, immediate feedback, and deductions after x attempts.
The user can download their grade to an html by including the grade_print_ui() function.
Shiny ui and server logic for the grade computation.
Note that when including these functions in a learnr Rmd document it is necessary that
the server function, grade_server(), be included in an R chunk where context="server" as
they interact with the underlying Shiny functionality. Conversely, the ui function,
grade_button_ui(), must not be included in an R chunk with a context.