Keys can be generated from two different CRS

[ureeves]

Describe the bug Currently 8 circuits can be compiled to produce their prover and verifier keys. For this process, a single CRS is lazily generated and cached for subsequent use. It is currently possible to generate the first few keys using make keys, cancel the process, delete the generated CRS, and happily rerun make keys. This will produce one set of keys compiled with the deleted CRS, and a set of keys compiled using the new CRS.

To Reproduce To make this happen, follow the following process:

source .env
make keys
# wait until "Fetching SendToContractObfuscated key from cache"
# and then press Ctrl+C to interrupt the process
rm .rusk/dev.crs
make keys

Expected behaviour We should be prevented from doing this. make keys should trigger a CRS rebuild when a different one is generated.