disable stake unlocks and keep blacklisted key images permanently

[darcys22]

No description provided.

[Doy-lee]

We probably want these checks to go in earlier, I believe we are still allowed to submit unlocks to the blockchain so we should reject these in the mempool and in blocks

Additionally we can let the blacklisted key images expire IIRC, you need to do a key image unlock to withdraw the funds after expiry. This allows SNs to eventually flush out this data if there are any instead of keeping them in perpetuity.

[jagerman]

We probably want these checks to go in earlier, I believe we are still allowed to submit unlocks to the blockchain so we should reject these in the mempool and in blocks

It doesn't really hurt if they go into mempool/blocks: they just need to get ignored instead of processed. This part of the PR got included in 74ed6b8

Additionally we can let the blacklisted key images expire IIRC, you need to do a key image unlock to withdraw the funds after expiry. This allows SNs to eventually flush out this data if there are any instead of keeping them in perpetuity.

We need to keep many of the key images permanently, but not all: nodes that are unregistered for transition will have their funds unlock and be spendable again, but transitioned nodes (which are issued SENT at HF21 in exchange for their OXEN) must not. I believe that's on @tewinget 's radar with WIP transition code.