Fix redirecting Eshell output to symbols in some places

Fix redirecting Eshell output to symbols in some places

* lisp/eshell/esh-io.el (eshell-output-object-to-target): Don't require
TARGET to be bound.

* lisp/eshell/em-script.el (eshell-execute-file):
* lisp/eshell/eshell.el (eshell-command): Quote the output/error
targets.

* test/lisp/eshell/em-script-tests.el (eshell-execute-file-output): New
variable.
(em-script-test/execute-file/output-symbol): New test.

* test/lisp/eshell/eshell-tests.el (eshell-command-output): New
variable.
(eshell-test/eshell-command/output-symbol): New test (bug#72857).

(cherry picked from commit e269cf63a67d529740d0ec2382ae7c3a982cd064)