This function opens the `tutorial.Rmd` file in RStudio for
interactive use. Users can then run each code chunk step by step.
Usage
open_tutorial()
Value
If successful, opens the `tutorial.Rmd` file in RStudio for the user to
interact with.
If `rstudioapi` is not installed or available, or the tutorial file is
not found,
an error is thrown with a corresponding message.