improve tests in Ldap.php class

[davidcoutadeur]

Currently, we can't test functions that require to modify the arguments passed by reference.

Typically, the ldap_parse_result function, but maybe also other functions.

This prevents from doing complete tests, especially with paged searches test with multiple pages.

So the goal is to improve theses test functions:

• test_search_with_page_size
• test_modify_attributes_using_ppolicy

and determine if there is any other LDAP function modifying variables by reference.

[davidcoutadeur]

See also bug opened on mockery project: mockery/mockery#1440