fix: remove iv reference from encryptionInformation.method

[strantalis]

Proposed Changes

This change would update the spec and remove IV from EncryptionInformation.Method as it seems unnecessary as it seems standard to prepend the IV to the cipher text. Also the current IV usage wouldn't work unless you reuse the IV for each chunk which we don't want to promote as it is bad practice.

This would be a PATCH as clients are already not using the IV in EncryptionInformation.Method.

Corresponding issue #22

Checklist

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