feat(soroban): support bytesN as function parameters and return values

[aryanbaranwal001]

Description

Adds support for bytesN (bytes1–bytes32) solidity function parameters or return types for the Soroban target. The following now compiles to valid WASM and round trips through the host.

contract BytesNCodec {
    function echo_bytes5(bytes5 x) public pure returns (bytes5) {
        return x;
    }
}

Key Changes

• codegen/encoding/soroban_encoding.rs: added Type::Bytes(n) arms to soroban_decode_arg and soroban_encode_arg. All 1 ≤ n ≤ 32 route through BytesObject via bytes_copy_to_linear_memory (decode) and bytes_new_from_linear_memory (encode), matching soroban-sdk's BytesN<N> wire format.

Tests

• Added 3 tests in tests/soroban_testcases/bytes_n_codec.rs covering narrow, non-natural, and wide LLVM integer widths.

[aryanbaranwal001]

This PR is continuation of the work in #1904 and depends on it.