Validator key decrypt

[sparrowDom]

Make it possible to decrypt a validator private key directly from S3 storage.

The following command using VALIDATOR_KEYS_S3_BUCKET_NAME=validator-keys-test should yield the following results

yarn hardhat decryptFromStorage --pubkey 0x8172ac384cade0b541c6b8fc486994e4d0a62fa0ed86bd3f8b6564106f2c223b7f274da673ff55e1c56d9b6428b06978 --displaypk true

Validator public key: 8172ac384cade0b541c6b8fc486994e4d0a62fa0ed86bd3f8b6564106f2c223b7f274da673ff55e1c56d9b6428b06978
Private validator key:  5a5f3f781842ee9097bf36895cb91f293950d1c5957fe9778d83afda91247322

Make sure to have the correct master encrypted validator private key configured

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 61.86%. Comparing base (c9f069e) to head (aa4108e).

:exclamation: Current head aa4108e differs from pull request most recent head 28696d6

Please upload reports for the commit 28696d6 to get more accurate results.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2111 +/- ## ======================================= Coverage 61.86% 61.86% ======================================= Files 66 66 Lines 3322 3322 Branches 863 863 ======================================= Hits 2055 2055 Misses 1264 1264 Partials 3 3 ```

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[sparrowDom]

thanks for all those changes!