Update the scripts template to make use of the new rust sdk functionality for updating and initializing contracts

[abizjak]

Task description

The deployment scripts that come with templates are a bit verbose. There is a lot of functionality in the Rust SDK that is not used, but should be.

• estimating and sending contract initializations and updates
• querying responses from those updates

We should implement that in the templates so that they become simpler and easier to understand.