You can now bulk load SECP keys for eth1

[bgravenorst]

See: Consensys/web3signer#892

SECP wallet files bulk loading in eth1 mode. Introduced following cli options:

--keystores-path The path to a directory storing v3 wallet files. Wallet files must use a .json file extension.
--keystores-passwords-path The path to a directory with the corresponding password files for the wallet files. Filename must match the corresponding wallet filename but with a .txt extension. This cannot be set if --keystores-password-file is also specified.
--keystores-password-file The path to a file that contains the password that all wallets use. This cannot be set if --keystores-passwords-path is also specified.