[i18n] cleanup dead code also fix small bug introduced in b0f6e8c14e7f

[i18n test] hack to make i18n tests run using a Python interpreter they used to work fine when executed via pytest only. This should be removed as soon as logilab.common.registry is fixed.

[i18ncube] fix crash due to duplicated messages in generated schema.pot Add a test case and fix regression introduced in e713c47a993d. Relates to #2811282

[i18n test] load_po: fix bug in case of multi-lines msgid and ensure there are no duplicated messages

[i18n test] simplify test cube a bit by only providing a views module, no package

[web] consider inlined relations in has_editable_relation. Closes #3049970 In some cases where the user can only add/edit inlined relations (though actually edit perms of the inlined relation doesn't seem checked), the "modify" action doesn't appear while it should.

[web test] silent 3.13 warning

[editcontrollers] Account for role in the ordering of entities (Complements #3031719) Only role='object' was correctly accounted for by 570208f74a84

[migration.sync_schema_props_perms] ensure all participants to a unique together constraint are there before adding CWUniqueConstraint. Closes #3038345

[session commit] save back exception context to avoid potentiel cluttering if some revert operation raise an exception