dnsdist: Ponder improvements to `DynBlockRulesGroup:excludeRange()`

[rgacogne]

• Program: dnsdist
• Issue type: Feature request

Short description

It would be nice to be able to:

• pass a NetmaskGroup to DynBlockRulesGroup:excludeRange()
• be able to replace the existing list of excluded domains in one go (as opposed to adding new entries to the existing ones), something like DynBlockRulesGroup:setExcludedRanges(NMG)