This means that Eshell globs can now expand the same way as if the
user had typed each matching file individually.

* lisp/eshell/em-glob.el (eshell-glob-splice-results): New option.
(eshell-no-command-globbing, eshell-add-glob-modifier): Handle spliced
globs.
(eshell-extended-glob): Always return a list when splicing.

* lisp/eshell/em-pred.el (eshell-parse-arg-modifier): Ensure
'eshell-splice-args' is always at the end of the list of modifiers if
present.

* test/lisp/eshell/em-glob-tests.el
(em-glob-test/expand/splice-results)
(em-glob-test/expand/no-splice-results)
(em-glob-test/expand/explicitly-splice-results)
(em-glob-test/expand/explicitly-listify-results): New tests.
(em-glob-test/no-matches): Check result when
'eshell-glob-splice-results' is nil/non-nil.

* doc/misc/eshell.texi (Arguments): Expand explanation about argument
flattening.
(Globbing): Document splicing behavior of globs.

* etc/NEWS: Announce this change.

* lisp/eshell/em-glob.el (eshell-glob-convert): Return whether to
match directories only.
(eshell-glob-entries): Add ONLY-DIRS argument.

* test/lisp/eshell/em-glob-tests.el
(em-glob-test/match-any-directory): New test.
(em-glob-test/match-recursive)
(em-glob-test/match-recursive-follow-symlinks): Add test cases for
when "**/" or "***/" are the last components in a glob.

* etc/NEWS: Announce this change (bug#56227).

* lisp/eshell/em-glob.el (eshell-glob-recursive): New variable.
(eshell-glob-convert-1, eshell-glob-convert): New functions.
(eshell-extended-glob): Use 'eshell-glob-convert'.
(eshell-glob-entries): Adapt function to use pre-converted globs.

* test/lisp/eshell-em-glob-tests.el (em-glob-test/match-dot-files):
New test.

* lisp/eshell/em-glob.el (eshell-extended-glob): Fix docstring.
(eshell-glob-entries): Refer to '**/' in error (technically, '**' can
end a glob, but it means the same thing as '*').  (Bug#54470)

* test/lisp/eshell/em-glob-tests.el: New file.

* doc/misc/eshell.texi (Globbing): Document pattern-based globs.