feat(cu): allow force to bypass cached nonce error

[jfrain99]

Background

Currently, if you try to access the result of a message which is earlier than the lastest cached memory, the CU will throw an error ("error": "message at nonce ... not found cached, and earlier than latest known nonce ...").

Issue

Even if we have a later cached nonce, sometimes we will want to bypass this and get the result anyways.

Solution

Create an opt-in config var, allow_force, which when active will read the result endpoint for a query parameter called force. If present, the CU will bypass the above error, skip the later cached nonce, and continue searching.