bug: RLN validator is only added for statically configured pubsub topics

[gabrielmer]

Problem

Currently, when RLN is enabled, RLN validator is added only for pubsub topics added at node initialization

nwaku/waku/node/waku_node.nim

Line 983 in 8a9fad2

node.wakuRelay.addValidator(pubsubTopic, validator)

For dynamically added topics, RLN validator is not set even if node is running with RLN enabled.

In go-waku, if rln is enabled the RLN validator is added to defaultTopicValidators which are set to any pubsubTopics subscribed after initialization:

• https://github.com/waku-org/go-waku/blob/190d8e8e0881bdcfba0d6fa220abfb05066b9f44/waku/v2/node/wakunode2_rln.go#L94
• https://github.com/waku-org/go-waku/blob/190d8e8e0881bdcfba0d6fa220abfb05066b9f44/waku/v2/protocol/relay/validators.go#L42

Expected behavior

If RLN is enabled in the node, all the pubsub topics must run the RLN validator