[ldap] Major test refactoring Mostly fix tests (previous refactoring), but also refactor a bit the base class to have better/simpler interaction with the slapd server.

[test/ldap] have RQL2LDAPFilterTC use its own database I do not know what RQL2LDAPFilterTC is about and why it does this strange reuse of LDAPUserSourceTC pre_setup_database but it is certainly a good idea to have it use a dedicated database-cache.

[ldap] quieter tests Capture slapadd and slapd output if everything goes well.

[test/ldap source] better source naming, some cleanups (prepares #2528116) ldap uri becomes "ldap" in all cases prepare separation of CONFIGs by source type

use cw_etype instead of __regid__ We have a clean public API now.

[entity] add an official ``cw_etype`` property for entity This property holds the CWEtype id of the entity. This information was previously available through __regid__ but this is an ugly public API. So we have a new clean public API. The ``dc_type()`` method could not be used as it is translated. (closes #2793792)

[notification] use new style operation for notification This results in far less operations created. Operation creation is expensive. We keep some compatibility with the previous API because some cubes have been reported to use it.

[cleanup] drop code deprecated since 3.6 The 3.6 API have been dropped some time ago. Those three lines survived the purge. One of them is even deprecated since 3.5.

[notification] fix documentation The doc say precommit, the code says postcommit. The code is right. We also clarify the documentation of another related operation looking suspiciously wrong but actually correct.

[ldapuser] Deprecated the source We have ldapfeed for some time. maintaining both is cumbersome. This old style source will be dropped in 3.18. closes #2567712

[rql2sql] Remove an XXX by explaining why Int non-substitution is desired (in the current state of the API)

[rql2sql] Boolean values should be substitued like others. Closes #2829481 Furthermore lgdb 1.10 deprecate boolean_value method and this simplify testing.