Default is to use 'eid' but one may want to use something
else (stable id, ark, etc.)

closes #17079908

* get rid of CUSTOM_ATTRIBUTES. Replace it with IFullTextIndexSerializable adapter `custom_indexable_attributes`
  attribute;
* FullTextIndexSerializable.serialize method : default complete value is now True*


closes #17079905

CubicWebConfig.config_for might accept extra parameters such
as "debugmode"

--debug and --dry-run should be used as flag-only options.
They don't expect a "yes" / "no" value.

Also, remove tests on stdout in debug mode because it's
fragile and messes up with logging handling in cubicweb.

It's not used (and therefore not real-life-tested) anywhere
and current implementation is known to be partial and a bit
hard to maintain.

(closes #17071989)

closes #17052625

FTI update is now done at commit time in an operation,
we need to call commit() to trigger it

[test] only check composed search doesn't crash, the query is too unstable to maintain tests for now

Also : ccplugin - generator serves all actions, not split up by type
       es.py - add CUSTOM_ATTRIBUTES mechanism