fix: PackFile::getBakeOutputDir unable to recognize parent directory of original file with backslash

[Starfelll]

No description provided.

[craftablescience]

The true fix is fixing up the slashes directly when this->fullFilePath is set in the constructor, as the code assumes everywhere that it's using normalized slashes when it possibly isn't.

This change at L109 should be all that's required to fix the bug:

PackFile::PackFile(std::string fullFilePath_)
-		: fullFilePath(std::move(fullFilePath_)) {}
		: fullFilePath(std::move(fullFilePath_)) {
+	string::normalizeSlashes(this->fullFilePath);
+}