Resolve "Refactor path resolution"

Refactors path resolve mechanism and adds two new CMake options:

• GKFS_USE_LEGACY_PATH_RESOLVE - Use the legacy implementation of the resolve function, deprecated (default: OFF)
• GKFS_FOLLOW_EXTERNAL_SYMLINKS - Enable support for following external links for resolving the path (default: OFF)
  • This is automatically enabled in the deprecated version and causes an lstat() system call on each individual path component. This has been an issue in the past where performance was considerably impacted by the mountpath being placed within the parallel file system.
  • It is now disabled by default to improve performance. In case, it causes issues, we can re-enable it.

Closes #281 (closed)