Prepare an RFP for the external audit

[ffakenz]

Why

We want an external auditor to review our specification and implementation. For that we shall go through a Request for Proposal (RFP) process to get bids of potential auditors.

What

Our project is very similar to Marlowe and Mamba, who are also going through that process right now. We want to draft an RFP similar to theirs.

Also, the CIP-52 is a good reference to "what it takes to audit an DApp"

The audit shall focus on the crucial parts first (as also argued in the other RFPs) and that is, the specification and on-chain code.

We should aim to audit version 0.9.0 (when we have addressed the known gaps in #452)

An RFP has been drafted (internal doc for now): RFP

How

• Create an RFP scope
• Await for CM approval
• Fill the RFP scope into the template
• make it flow through the RFP process

[ffakenz]

Related PR: #607