Issue 50869 - Setting nsslapd-allowed-sasl-mechanisms truncates the value
Bug Description: Adding multiple mechanisms to nsslapd-allowed-sasl-mechanisms ignores all but one of the mechanisms specified.
Fix Description: The issue happens because we use the same memory address
for 'char *' for slapdFrontendConfig->allowed_sasl_mechs and
for slapdFrontendConfig->allowed_sasl_mechs_array.
So when we split the 'char *' into the 'char **' with ' ' delimetr,
allowed_sasl_mechs has only the first element becuase ' ' is set to 0 now.
Define a separate 'char *' for the array.
Add a test for the issue.
https://pagure.io/389-ds-base/issue/50869
Reviewed by: mreynolds, firstyear, tbordaz (Thanks!!)