Retrieves every key inside hash_table. The returned data is valid
until changes to the hash release those keys.
This iterates over every entry in the hash table to build its return value.
To iterate over the entries in a glib.HashTable more efficiently, use a
a GList containing all the keys
inside the hash table. The content of the list is owned by the
hash table and should not be modified or freed. Use g_list_free()
when done using the list.