Give contract authors control over optimization passes

[cmichi]

Motivation

In src/cmd/build.rs we currently pass the number of optimization passes 3 to binaryen by default. However, it is desirable to give contract authors control over this setting. Hence we want to expose it on the cli.

ToDo

• cargo contract build should have an additional --optimization-passes parameter which makes this variable customizable.

[clearloop]

Hi @cmichi , we have a modification in #131 related to the opt passes, if there is any plan on the wasm optimization in cargo-contract, please ping us ( @patractlabs )

[ascjones]

In addition we could allow this to be configurable via a custom section in a contract's Cargo.toml.