Add LDAP channel binding support

[moscowchill]

• Add --ldap-channel-binding CLI option for servers requiring channel binding
• Implement TLS channel binding using ldap3 >= 2.10
• Add helpful error message when strongerAuthRequired (result code 8) is received
• Check for TLS_CHANNEL_BINDING attribute availability before attempting to use it

This allows ldapdomaindump to work with domain controllers that have LDAP channel binding enforced.

Requires: ldap3 >= 2.10 (pip3 install git+https://github.com/cannatag/ldap3.git)

[moscowchill]

@dirkjanm @spextat0r This is a refresh of #57 - the original PR referenced ly4k's ldap3 fork which is now archived. Channel binding support has since been merged into the official ldap3 repo (cannatag/ldap3#1087) and will be available in ldap3 >= 2.10.
Until 2.10 is released on PyPI, users can install from master:
pip3 install git+https://github.com/cannatag/ldap3.git
Also adds a helpful hint when strongerAuthRequired error is received, pointing users to the --ldap-channel-binding option. Tested against a DC with channel binding enforced.

[Neustradamus]

@moscowchill: Nice, thanks for your PR about TLS Channel Binding!

Linked to:

• State of Play scram-sasl/info#1