[SPIKE] Better developer experience when working with handlebars templates

[c12i]

With more changes getting made to the template, its time we consider the developer experience for holochain devs working on or reviewing these files

Spike Goals:

• How to improve readability of the templates.
• How to integrate a handlebars formatting tool
• How to add lint checks for handlebars templates
• How to test the templates
• Explore editor tools that can improve syntax highlighting

[mattyg]

A few ideas I have that might be good leads:

• An "extensive" example template that covers all the conditional rendering available in scaffolding (not sure if the forum example covers everything)
• A dev:watch command that watches the templates dir for changes, and then regenerates the extensive example for all frameworks, so the developer can quickly see template changes reflected in a built examples
• Using "yaml frontmatter" in the templates to set variables to the result of some logic, and then use those variables throughout the template rather than repeating the logic
• Rename the file based on a yaml frontmatter variable "file_name", instead of parsing the actual file name as its own handlebars template.