Support expanding Eshell globs for remote file names

Support expanding Eshell globs for remote file names

* lisp/eshell/em-glob.el (eshell-glob-chars-regexp): New function...
(eshell-glob-regexp): ... use it.
(eshell-glob-p): New function...
(eshell-glob-convert): ... use it, and return the deepest start
directory possible.

* lisp/eshell/esh-util.el (eshell-split-path): Rename to...
(eshell-split-path): ... this, and account for remote file names.

* test/lisp/eshell/em-glob-tests.el
(em-glob-test/convert/current-start-directory)
(em-glob-test/convert/relative-start-directory)
(em-glob-test/convert/absolute-start-directory)
(em-glob-test/convert/remote-start-directory): New tests (bug#69592).

(cherry picked from commit e42f14f0e034d0b20c6b9fd0fea23686699e7df0)