util: Rename function to calls_find_in_model() and adjust documentation

Since it works for GListModel rename it appropriately.

It used to provide an inline implementation for g_list_store_find()
behind a glib version guard, but we bumped minimum version in
cfd3c2a7fe
so the docstring was updated and made more succinct.

src/calls-manager.c

@@ -518,7 +518,7 @@ origin_found_in_any_provider (CallsManager *self,
     CallsProvider *provider = CALLS_PROVIDER (value);
     GListModel *origins = calls_provider_get_origins (provider);
 
-    if (origins && calls_find_in_store (origins,
+    if (origins && calls_find_in_model (origins,
                                         origin,
                                         &position))
       return TRUE;