rcpputils::fs::create_directories doesn't check if an existing path is a directory

[christophebedard]

Calling rcpputils::fs::create_directories on /a/b/c/d, where d is a file and not a directory, will return true (assuming that /a/b/c/ exists) because it only checks that the path exists.

rcpputils/include/rcpputils/filesystem_helper.hpp

Line 506 in 5e98497

if (!p_built.exists()) {

One could simply call is_directory to double check, but looking at the documentation, I don't think that's right:

rcpputils/include/rcpputils/filesystem_helper.hpp

Line 493 in 5e98497

* \return Return true if the directory is created, false otherwise.