Mark `salishsea_tools.tidetools.get_dfo_wlev()` as deprecated

[douglatornell]

Parker reported on 22-Jan-2025 that salishsea_tools.tidetools.get_dfo_wlev() raises errors. It is very old web form scraping code.

It and salishsea_tools.tidetools.get_all_perm_dfo_wlev() need to be marked as deprecated with salishsea_tools.data_tools.get_chs_tides() as the recommended alternative.