Implement build system and automated testing for templates & examples

[peppergrayxyz]

I'd like to propose to further productize w4 by implementing a build command, that builds the project and downloads build tools if needed. Also, I would like to include this tool into the pipeline, to build templates and example to check if they are working.

Proposal

1. fixing templates
   some templates are broken

2. fix guide
   some templates are not in the guide

3. harmonize paths
   harmonize paths where possible src, build/cart.wasm, update watch logic, generate deprecation notice for existing repos + info what to change to adhere to uniform paths

4. build script (draft)
   create a build script to be used by GitHub actions

5. harmonize templates
   some templates implement different logic

6. create test cases
   create two tests for the templates, one with the start screen and one with x pressed to verify that they are working

7. create Contribution Guidelines for new templates
   explain how to create a new template and how it fits in the structure

8. Move build logic from scripts to cli.js
   create a proposal how w4 build would work and implement it

9. Bonus: Port everything to WASM
   once everything is automated, we can think about how to do it in a browser & have a web IDE