Submit/Evaluate transaction flow should ask for channel

[EdMoffatt]

When doing a submit or evaluate via the Command Palette, you're asked to select:

• Gateway
• Identity
• Smart Contract

Because you can have a smart contract of the same name and version instantiated on 2 channels, that means you can end up selecting from a list like this:

I think we need to add in a step of selecting your channel in between the Identity and Smart Contract steps.