[web/request] Restore attribute setting for search_state This was dropped in 1f84295bfe95 when `search_state` attribute was turned into a property, but without a setter. So adding a setter here restoring previous behaviour, as some tests and cubes use it. Related to #4875761.

[web/request] simplify search_state loading, fix comment

[webrequest] Lazy-load search_state - The update_search_state function will hit the session data only if __mode is present in the form. - set_search_state keep the same semantics - Direct access to search_state in the session data is changed by an access to the new property. Closes #4875761

[config] disable fckeditor by default (closes #1368900) FCKEditor is no longer maintained, and has a history of XSS issues. Let's use plain text as default text format.

merge 3.19.11 into 3.20

Added tag cubicweb-version-3.19.11, cubicweb-debian-version-3.19.11-1, cubicweb-centos-version-3.19.11-1 for changeset 1ae64186af94

[migration] reorder system tables / meta-schema migration into bootstrap_migration Also fix a bug in the backwards-compat eid_type_source method where it returned an extid (possibly null) instead of a source name. With these changes, migrating a database from cw 3.12 is now possible. Closes #4962681

[dataimport] add missing import (closes #4985916)

[debian] cubicweb-dev needs cubicweb-etwist Closes #4965410

[pkg] 3.19.11