fix: adds EIP1271 to supported signature type

[parseb]

Adds EIP1271 signature type to signer registry graph

[parseb]

What is the bug?

The Specification mentions only ECDSA signature support for managing signers.
The validator calls the registry's verifyFidSignature which makes use of OpenZeppelin's SignatureChecker util which supports EIP1271 signature.
As such, the signature is validated by the issuing smart contract and not by ECDSA recovery.

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/e50c24f5839db17f46991478384bfda14acfb830/contracts/utils/cryptography/SignatureChecker.sol#L43

How can it be reproduced? (optional)
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Additional context (optional)
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