Shutter API Continuous Test

[ylembachar]

To ensure decryption functionality in the absence of metrics from other keypers, we need a mechanism to verify that decryption works at a set interval. This requires a small test set that registers an identity with a decryption trigger after a short delay. After the delay, the system should verify that the decryption keys have been released. The interval for these checks should be configurable.

[blockchainluffy]

The PR is tested and updated, ready to be reviewed.