cpp/path-injection Overhaul

[bdrodes]

I received false positive reports on https://github.com/microsoft/codeql/blob/bbdf97e8f3acb64be15ca59a3ae3366cd6fc8cd5/cpp/ql/src/Security/CWE/CWE-022/TaintedPath.ql
(cpp/path-injection). The users were attempting to filter the paths by looking for ".." but the path still appears vulnerable. One example provided was something like this if (pathString.find("..") != std::string::npos). Generally, the query relies on hasUpperBoundCheck, but this may need to be updated to match similar queries in other languages.