Merge branch 'jathenst/281-refactor-path-resolution' into 'master'

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

Closes #281

See merge request !183