feat: Autosharding protocol changes for req-resp protocols

[chair28980]

This tracks work necessary to change req-resp protocol requirements for pubsub topic fields to be optional in wire specifications. This implies a spec change, changes to clients to use the simplified specs and changes to server-side Waku implementations to interpret client requests with no populated pubsub topics correctly.

specification: @SionoiS

Priority: Not critical for launch (all main benefits of autosharding is already achieved via API changes)

[chair28980]

https://github.com/waku-org/research/issues/3

@danisharora099 @weboko

Per the research issue, can y'all verify if this is required for JSWaku and assign ownership as necessary. Thank you!

[fryorcraken]

See https://github.com/waku-org/nwaku/issues/1937#issuecomment-1778308708

[chair28980]

Iceboxing per above reference. https://github.com/waku-org/nwaku/issues/1937#issuecomment-1778308708

Iceboxing this as it's a cleanup/nice to have that does not have strong added value.

May be done if it allows to simplify code/logic to enable work in the area.