Create a reporting function for waiting list pressure across multiple sites and specialties

[ThomUK]

Take the output from the calculation function written in issue #25, and use it to produce an Rmd or Quarto html report summarising and visualising the waiting list position.

The return will be an html report containing an overview of the waiting list, and a dynamic table allowing various columns to be sorted (eg. by highest pressure, longest wait, etc). It may also contain some overview charts (eg comparing hospital sites, specialties, etc).

[jacgrout]

I'm keen to help with this issue

[chrismainey]

Much of this is handled in the wl_stats function. Might want to wrap a nice output format on to it in future.