Introduce new misc type for module function

Introduce new misc type for module function

This resolves a couple of FIXMEs in emacs-module.c.

* src/lisp.h (MODULE_FUNCTIONP, XMODULE_FUNCTION): New functions.

* src/alloc.c (make_module_function): New function.
(mark_object): GC support.

* src/data.c (Ftype_of, syms_of_data): Handle module function type.

* src/print.c (print_object): Print support for new type.

* src/emacs-module.c (module_make_function, Finternal_module_call):
Use new module function type, remove FIXMEs.
(module_format_fun_env): Adapt and give it external linkage.

* test/src/emacs-module-tests.el (module-function-object): Add unit
test.