Given a string with environment variables (encoded like ${VAR} or $VAR), and
other variables (encoded like {VAR}) this function will substitute
both of these and return the formatted string, like the Python
str.format() method. Other variables are populated from a list of arguments.
Additionally, if the string is a non-absolute path, it will be expanded.
.strformat(string, args, parent = NULL)String with variables encoded
named list of arguments to use to populate the string
a directory that will be used to make the path absolute
Formatted string