xgettext: Rust: Support --keyword option with a qualified name for macros.

xgettext: Rust: Support --keyword option with a qualified name for macros.

Reported by Lucas Baudin <lbaudin@gnome.org>
at <https://savannah.gnu.org/bugs/?68297>.

* gettext-tools/src/x-rust.c (extract_from_function_call_like): Use the
accumulated qualified name also for macro invocations.
(extract_from_node): Allow generic identifiers also for macro invocations.
* gettext-tools/tests/xgettext-rust-9: New file.
* gettext-tools/tests/Makefile.am (TESTS): Add it.