cli: Input validation and Commander.js scripting with themes

[winstonwumbo]

New Features

• Added CLI options for --custom-theme-name and --custom-theme-template to Commander.js
• hax-create will throw an error if the options are scripted without --theme custom-theme
• Clack prompts will validate if the theme name is already part of the HAX core themes, has valid formatting, etc.
• Refactored the customSiteTheme function in siteProcess to respond to either commandRun or project inputs
• customSiteTheme uses some regex to apply our naming requirements (custom-${name}-theme) before deploying the webcomponent

Related Issue(s)

• [cli] Adding custom element to site custom build routine for custom webcomponent / hax theme development issues#2196
• theme development workflow for local developers issues#2023