feat(remote): add directory listing and create_session directory (#13497)

* feat(remote): add directory listing and create_session directory

* fix(remote): harden list_directories containment and per-entry skip

* fix(remote): reject a missing directory under a symlinked ancestor

Filesystem.resolve returns the lexical path on ENOENT, so a requested
path whose final component does not exist skipped canonicalization. A
symlinked ancestor that points outside the launch directory then passed
the containment test. Require the target to exist and be a directory
before canonicalizing.