POC: JavaScript expressions in brick args

[twschiller]

What does this PR do?

• Quick POC to evaluate gaps for supporting writing JavaScript directly
  • Goal: evaluate the feasibility of eliminating need to users have to learn Nunjucks text template syntax
• Implements:
  • Add javascript expression type
  • Javascript toggle mode
  • Javascript renderer using existing Sandbox
  • Javascript expression analysis

Gaps

• I didn't update the snapshot test
• Variable dereference character @ is not valid in JS identifiers. (It's also a bad character because @ toggles username popups in many collaboration tools)
  • A quick way to roll out to advanced users would be to make the variables accessible via a $vars object, e.g., $vars["@input.url"].length
  • We could write a custom lexer to transform @<ident> to $vars["<ident>"] automatically. That's what val.town used to do (IIRC, they used a custom babel plugin to do that). They then moved to vanilla JS syntax to better benefit from the JS tooling ecosystem
• Would need a JS tokenizer, e.g., https://github.com/lydell/js-tokens for variable popover

Demo

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[github-actions]

Playwright test results

 154 passed
 2 skipped

Details

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 156 tests across 51 suites
 11 minutes, 43 seconds
 5a78226
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Skipped tests

chrome › tests/runtime/googleSheetsIntegration.spec.ts › can activate a google spreadsheet mod with config options
msedge › tests/runtime/googleSheetsIntegration.spec.ts › can activate a google spreadsheet mod with config options