Approve multiple tokens in ONE transaction!
User signs ONCE, and all tokens are approved for spending by a specified wallet
Parameters:
fn approve_multiple(
env: soroban_sdk::Env,
owner: soroban_sdk::Address,
spender: soroban_sdk::Address,
tokens: soroban_sdk::Vec,
amounts: soroban_sdk::Vec,
expiration_ledger: u32,
) -> Result<(), ApproveError>