[views] simplify and fix the TreeView (closes #16055814) Simplify the (internal) TreeView._init_params() method to get rid of the useless 'initial_thru_ajax' argument. The ajax tree view was not working properly when loaded via ajax, for instance from a lazy tab. This was due to the buggy protection against double javascript/ css inclusion, which is no more needed server-side as it is now implemented client-side. Deprecate use of the initial_thru_ajax argument of the TreeView.call() method.

^build$
^dist$
\.egg-info$
^.tox$
^.cache$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/libpython/cubicweb_.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/
test-results.xml