fix: synchronous validateReceivedMessage

[twoeths]

Motivation

• some duplicate messages were sent to lodestar to uncompress due to async validateReceivedMessage(), see #535

Description change validateReceivedMessage() implementation to be synchronous:

• make msgIdFn() synchronous, switch to use @chainsafe/as-sha256 for this
• move topic validation outside of validateReceivedMessage()
• move validateToRawMessage() out of validateReceivedMessage()
  • separate to synchronous validateStrictNoSignMessage()
  • and async validateStrictSignMessage()

Closes #535