Substrate: Event decoding does not match `ink!`

[xermicus]

          Found it.
          https://github.com/paritytech/cargo-contract/blob/ce9afac78eb76aa1c78998e08861764619f5e8ff/crates/transcode/src/lib.rs#LL293C9-L293C50
         
          This file strips one `Compact<u32>` where solang generated event doesn't have. If we manually prepend one into the Event.data field, the decoding will success.

Originally posted by @extraymond in https://github.com/hyperledger/solang/pull/990#discussion_r1233860135