[common_test] Added tests and corrected bugs in ct_snmp

OTP-10454
OTP-10434

Function register_users/2, register_agents/2 and register_usm_users/2,
and the corresponding unregister_*/1 functions were not
executable. These are corrected/rewritten.

Function update_usm_users/2 is removed, and an unregister function is
added instead. Update can now be done with unregister_usm_users and
then register_usm_users.

Functions unregister_*/2 are added, so specific users/agents/usm users
can be unregistered.

Function unload_mibs/1 is added.

Overriding configuration files did not work, since the files were
written in priv_dir instead of in the configuration dir
(priv_dir/conf). This has been corrected.

Minor updates to documentation.

0 files changed, 0 insertions, 0 deletions