Added r-stringr

Added r-stringi

Added r-cpp11

Added r-purrr

Added r-dbi

Added r-blob

Initial commit

A long journey to packaging r-tidyverse. The current highest-level
packages that are successfully built are dtplyr, waldo, callr, and xml2.
A handful of others (brio, digest, praise, units, zeallot) are currently
freestanding but will become dependencies soon.