Support Deserialization of fields when they have fixed-size

[ERoydev]

What

When in the client the user needs to deserialize(read) a field, when he reads the blockchain state for a certain account from his anchor deployed program.The dart-renderer should handle fixed-sized fields(arrays, etc..) in the readBorsh methods because it needs to know how much bytes(how long is the field) to take from the buffer to show the correct value.

I tried to handle that in a more abstract way, specifically from the visitors, but I struggled a lot there because the visitor passes recursively and I needed to have all that information in TypeManifest instead of me modifying a specific node. That is why I decided to keep using Aleksandar’s approach for using regex and comments, which i have extended.

Key Changes

• Added support for fixed/variable-length arrays in readers/writers.
• Standardized discriminator read/write helpers across accounts and instructions.
• Expanded BinaryReader/BinaryWriter with array utilities and stricter validation.
• Improved type manifest parsing with array length and option handling.
• Refined visitor logic for structs and inline annotations.