tests: Use the connection's log domain in the handler
tests: Let ews_test_data_free() NULL-safe
Bug #712179 - Cannot create calendar object: The property is deprecated for this version of Exchange.
Add e_ews_debug_get_server_version_from_string()

Convert the server version from a string to an EEwsServerVersion is
(only) used in our tests, where we firstly set the server version as
a string, before create the connection*, and we need to check which
versions are supported or not by a specific test.

*connection is created latter when we are running tests offline.
tests: Add tests to GetServerTimeZones operation