1248 - Introducing the factory pattern

[ipopescu]

What does this PR fix/introduce?

Add initial documentation on the factory pattern for contract authors. Closes #1248

Additional context

• Contract: https://github.com/mpapierski/casper-node/blob/gh-2064-factory-pattern/smart_contracts/contracts/test/counter-factory/src/main.rs
• Tests: https://github.com/mpapierski/casper-node/blob/gh-2064-factory-pattern/execution_engine_testing/tests/src/test/counter_factory.rs#L87C4-L87C54
• Recording and notes shared separately

Future work:

• I recommend creating some diagrams as part of another task:
  • a UML diagram explaining the factory pattern on Casper (entry points being the factories)
  • a diagram explaining the keys and contexts when using the factory pattern
• I recommend writing another step-by-step tutorial using the Casper client under (/tutorials) or (/cli) for deploying and using the counter factory contract (on the Testnet or NCTL).
• Finally, we need to decide whether to point to the casper-node as I did here (and wait for the future 2.0 branch), or put the counter factory example in the tutorials example wasm repository.
• FYI: I avoided saying “factory contract”, unless I had to simplify the explanations. I tried to say “factory pattern” and “factory entry point” instead.

Checklist

• Docs are successfully building - yarn install && yarn run build.
• For new internal links I used relative file paths (with .md extension) - e.g. ../../faq/faq-general.md - instead of introducing absolute file path, or relative/absolute URL.
• All external links have been verified with yarn run check:externals.
• My changes follow the Casper docs style guidelines.

Reviewers

@ACStoneCL and @mpapierski
FYI @ramujin and @ShalmaliCL

[github-actions]

🚀 Deployed on https://65bc11114211410fd87be9dc--sensational-creponne-f0e56d.netlify.app

[ACStone-MTS]

A few small nits in the interim.