Add Stylus script example to the template

[reo101]

Description

Context

Introduce scripting templates into the boilerplate that can be executed using cargo stylus script (see related cargo-stylus PR here)

Note

The branch is not ready to be merged yet, there’s a couple of commits that out fork is lacking, we’ll merge them in soon
OffchainLabs:main merged!

Changes

• Add deploy_and_interact script
  • Replaces old counter.rs example
  • Currently relies on a common library, shipped alongside the script, with the intention of moving that library into the cargo-stylus lib crate.
  • The common crate houses utilities for reading network configurations, creating provider and wallet instances, based on those configurations, and a function to aid the deployment of the main contract
    • The deployment helper can be extended to accept a contract name when/if Stylus starts supporting the definition of multiple contracts in a single Stylus project
• Add Stylus.toml, containing network configurations
• Remove counter.rs from examples
• Update README.md to reflect those changes
  • Remove Calling Your Program section
  • Add Deploying + Interacting with scripts section

Checklist

• I have documented these changes where necessary.
• I have read the DCO and ensured that these changes comply.
• I assign this work under its open source licensing.