Waku Message support version 1 (v1 waku envelope data format) for encrypted payload

[oskarth]

Problem

Currently we don't support encrypted payload. This has been speced out in https://specs.vac.dev/specs/waku/v2/waku-message.html#version-1 Basically it amounts to re-using already implemented code in Waku v1.

Acceptance criteria

WakuMessage v1 with encrypted payloads is supported.

Notes

There are probably some gotchas here in terms of how code is structured for Waku v1. This issue can possibly be broken down further. @kdeme any thoughts?

The payload for v1 is defined in nim-eth: https://github.com/status-im/nim-eth/blob/master/eth/p2p/rlpx_protocols/whisper/whisper_types.nim#L45

For usage, see https://github.com/status-im/nim-waku/blob/master/waku/protocol/v1/waku_protocol.nim#L489

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Another issue after this is ensuring compatibility with Waku v1, e.g. with bridging or some standalone tests. Though this should be fine, assuming same keys and types are used.

[oskarth]

Simplest start here is probably to make a standalone test here with version filed in that tests de/encrypt using existing code for Waku v1, just putting it in a WakuMessage.

[oskarth]

I believe this was done in PR above.