Add `--verbose` mode to Wasmi CLI

[Tom]

I'd like to be able to avoid this message when running wasmi_cli:

executing File("examples/out/branch.wasm")::_start() ...

I'd prefer it off by default, reserved for verbose mode, but conservatively, some --quiet flag option could be available instead.

I'm happy to add --quiet on my end and submit a PR. Would this be ok?

[Robin Freyler]

Maybe it is indeed better to introduce a --verbose option to enable the current messages since that would reflect the default way that Wasmtime currently does with respect to non-warning or non-error messages.

Please feel free to open a PR to introduce this --verbose option to our Wasmi CLI tool. :)

[Tom]

Awesome. Thanks for the reply. I'll work on that!