fil_node_open_file_low() tries to close files from the top of
fil_system.space_list if the number of opened files is exceeded.

It invokes fil_space_t::try_to_close(), which iterates the list searching
for the first opened space. Then it just closes the space, leaving it in
the same position in fil_system.space_list.

On heavy files opening, like during 'SHOW TABLE STATUS ...' execution,
if the number of opened files limit is reached,
fil_space_t::try_to_close() iterates more and more closed spaces before
reaching any opened space for each fil_node_open_file_low() call. What
causes performance regression if the number of spaces is big enough.

The fix is to keep opened spaces at the top of fil_system.space_list,
and move closed files at the end of the list.

For this purpose fil_space_t::space_list_last_opened pointer is
introduced. It points to the last inserted opened space in
fil_space_t::space_list. When space is opened, it's inserted to the
position just after the pointer points to in fil_space_t::space_list to
preserve the logic, inroduced in MDEV-23855. Any closed space is added
to the end of fil_space_t::space_list.

As opened spaces are located at the top of fil_space_t::space_list,
fil_space_t::try_to_close() finds opened space faster.

There can be the case when opened and closed spaces are mixed in
fil_space_t::space_list if fil_system.freeze_space_list was set during
fil_node_open_file_low() execution. But this should not cause any error,
as fil_space_t::try_to_close() still iterates spaces in the list.

There is no need in any test case for the fix, as it does not change any
functionality, but just fixes performance regression.