Problem:
- Since c57f6b28d7#8519, sockets are created in ~/.local/… but XDG
spec says: "XDG_RUNTIME_DIR: Must be on the local filesystem", which
implies that XDG_STATE_DIR is potentially non-local.
- Not easy to inspect Nvim-created temp files (for debugging etc).
Solution:
- Store sockets in stdpath('run') ($XDG_RUNTIME_DIR).
- Establish "/tmp/nvim.user/" as the tempdir root shared by all Nvims.
- Make ok() actually useful.
- Introduce assert_nolog().
closes#3517closes#17093
f50135a32e