wwan: fix hide-disconnected default, plug dup() leaks, meson/man cleanup

- update(): only hide the module when hide-disconnected is set AND the
  modem is not in the CONNECTED state, instead of hiding it unconditionally
  (the module was invisible by default).
- free the gchar* returned by mm_modem_dup_physdev/
  mm_modem_dup_equipment_identifier/mm_sim_dup_operator_name.
- meson.build: drop duplicate libgps dependency, install the wwan man page.
- man: document hide-disconnected (replacing the unimplemented
  hide-failed/hide-disabled/hide-not-registered options).
- remove stray empty subprojects/.wraplock.

meson.build

@@ -561,7 +561,7 @@ endif
 if libmm_glib.found()
    add_project_arguments('-DHAVE_LIBMM_GLIB', language: 'cpp')
    src_files += files('src/modules/wwan.cpp')
-   #man_files += files('man/waybar-wwan.5.scd')
+   man_files += files('man/waybar-wwan.5.scd')
 endif
 
 subdir('protocol')