[Ethereum]: Add support for abi.encodePacked() | Resolves #3679

[theghostmac]

Description

This pull request adds support for abi.encodePacked() as described in issue #3679. The implementation follows the non-standard packed mode encoding, which concatenates types shorter than 32 bytes directly without padding or sign extension, encodes dynamic types in-place without the length field, and encodes array elements padded but in-place.

How to test

Reviewers can test the changes by running the included test cases that cover various scenarios for abi.encodePacked() encoding:

1. cargo test encode_packed_tokens
2. Specific test cases:
   • encode_packed_address
   • encode_packed_bytes
   • encode_packed_string
   • encode_packed_int
   • encode_packed_bool
   • encode_packed_uint
   • encode_packed_fixed_bytes
   • encode_packed_mixed
   • encode_packed_array

Ensure that all tests pass and verify the encoded outputs match the expected values.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• [x] Create pull request as draft initially, unless it's complete.
• [x] Add tests to cover changes as needed.
• [ ] Update documentation as needed.
• [x] If there is a related Issue, mention it in the description.

If you're adding a new blockchain

• [ ] I have read the guidelines for adding a new blockchain.