Add dnsbeEppPollResponse implementation

[Brianvanwessel]

What does it do?

Implements dnsbeEppPollResponse, which can be used to extract DNS Belgium specific information from EPP poll responses.

How to test

1. Generate or retrieve a DNS Belgium EPP poll message.
2. Verify that the poll response is parsed as a dnsbeEppPollResponse.
3. Confirm that DNS Belgium specific information can be successfully extracted from the response.