* httpcaddyfile: Change the parse rules when empty file or dotfile with a glob.
* Fixes#5295
* Empty file should just log a warning, and result in no tokens.
* The last segment of the path is '*', it should skip any dotfiles.
* The last segment of the path is '.*', it should read all dotfiles in a dir.
* httpcaddyfile: Regard empty files as import files which include only white space.
