add overview for system dependencies

[maxheld83]

Whenever I have to deal with system dependencies and want to avoid randomly adding apt-gets until "stuff works", I seem to be researching the same things:

• difference between build time and run time system dependencies
• programmatic approaches to parse/install system dependencies from DESCRIPTIONs SystemRequirements field.
  There seem to be three 😄, each with different target systems, data structure and APIs (also crosslisted in merge with r-system-requirements rstudio/shinyapps-package-dependencies#234):
  1. r-hub's {sysreq} / sysreqsdb backing the r-hub service
  2. rstudio's shinyapps-package-dependencies backing shinyapps.io
  3. rstudio's r-system-requirements driving RSPM
• which of these can I use for my target computing environment? (answer: use r-hub obviously, though you have to use one of the available Linux distros then)
• should I cache system deps in my CI? (github actions) If so, how?

Is this something that other people might be re-researching as well all the time?
Is there a good resource out there already?

If no, I'd be happy to pitch in a draft article about this, if the r-hub blog is an appropriate venue.
(I thought it might be, since for now anyway, sysreq is the answer for me).

[gaborcsardi]

This is great stuff, but the sysreqs stuff is under a large overhaul, and it would be best to blog about it in a couple of months.

[maelle]

https://blog.r-hub.io/2023/09/26/system-dependency/