Get the version of an installed (but not necessarily running) RStudio
Source:R/programs.R
get_installed_rstudio_version.RdOn Windows, prefers the Version value written to the registry by the
installer (the VERSION file on disk can hold an unrelated Electron shell
build number on newer RStudio releases). Falls back to parsing the
VERSION file that RStudio Desktop places in its install directory.
Value
A numeric_version() object, or NULL if it could not be
determined.