Fix size_of calculations for dynamically sized types in Lazy

[jamie-osec]

This PR addresses two issues with Lazy which resulted in miscalculations for dynamically sized types.

• Enums: Enums are encoded with a tag byte before the payload. The size_of calculation for the inner data was passed the full data including the tag byte, instead of the actual inner payload, resulting in potential size miscalculations
• Arrays: Previously, the size of the first element was calculated, then multiplied by the array length. This is incorrect, as an array of dynamically sized types (e.g. [String; 5]) have non-homogenous sizes. Correct this by calculating the size of each element

This can result in incorrect deserialisation, allowing malicious payloads to bypass security checks.

[vercel]

@jamie-osec is attempting to deploy a commit to the Solana Foundation Team on Vercel.

A member of the Team first needs to authorize it.

[acheroncrypto]

The enum fix looks very elegant 👍

[swaroop-osec]

@jamie-osec Could you please update CHANGELOG as well?