[dataimport] dispatch and deprecate old code
previously, the whole dataimport.py content has been copied in
dataimport/__init__.py, then dataimport/importer.py API has been introduced.
Following these changes, this cset:
* dispatch __init__ code into sub-modules
* dispatch unittest_dataimport accordingly
* deprecates functions and classes that are deprecated by the new API
Related to #5414753.
.. _resources:
Locate resources
----------------
.. automethod:: cubicweb.web.webconfig.WebConfiguration.locate_resource
.. automethod:: cubicweb.web.webconfig.WebConfiguration.locate_doc_file
.. automethod:: cubicweb.web.webconfig.WebConfiguration.locate_all_files
Static files handling
---------------------
.. autoattribute:: cubicweb.web.webconfig.WebConfiguration.static_directory
.. automethod:: cubicweb.web.webconfig.WebConfiguration.static_file_exists
.. automethod:: cubicweb.web.webconfig.WebConfiguration.static_file_open
.. automethod:: cubicweb.web.webconfig.WebConfiguration.static_file_add
.. automethod:: cubicweb.web.webconfig.WebConfiguration.static_file_del