Add ZDI authority

MSP-9325
Filter invalid children from union operations.

MSP-9277

Filter invalid children before adding them to
Metasploit::Model::Search::Operation:Union#children so that invalid
children won't stop the union from validating, which can cause
deprecated operators to fail.

(cherry picked from commit abb187e)
Fix format of ZDI designation sequence

MSP-9325

Number after 2 digit year should only have 3 digits, not 4.
Merge pull request #12 from rapid7/feature/zdi-authority

ZDI Authority
MSP-9325