NodeBroker: delta protocol with incremental updates

[snaury]

• Write RFC
• Implement blue-green workaround
• Merge blue-green workaround to 24-3
• Merge blue-green workaround to 24-2
• NodeBroker refactoring?
• DynamicNameserver refactoring?
• Implement delta protocol in NodeBroker
• Implement delta protocol in DynamicNameserver

[snaury]

Closing in favor of #11064.