Does the return data of precompile need abi.encode?

[wuminzhe]

I prefer to remove abi_encode_bytes as it adds an unnecessary encoding and decoding process.

Ok(PrecompileOutput {
    exit_status: ExitSucceed::Returned,
    cost: helper.used_gas(),
    output: abi_encode_bytes(&output.unwrap_or_default()), <---
    logs: Default::default(),
})

[boundless-forest]

It's not entirely correct. If playing with smart contracts with remix, it will do ethabi decode automatically. If we remove it, the code remix shows are wrong.