bug/issue 1319 expand support for custom resource plugins like in frontmatter imports

[thescientist13]

Related Issue

resolves #1319

Summary of Changes

1. Extend layout utilities to account for custom formats inside frontmatter imports
2. Refined TypeScript to better support multiple use case (though a more thorough review should happen as part of leverage Sec-Fetch-Dest header for better filtering within Greenwood resource plugins #1222)
3. Did some async refactoring to ensure predictable results (though a more thorough review should happen as part of make Greenwood CLI and plugins async through and through #823)
4. Addressed an existing issue where custom CSS formats would not get properly bundled (could be its own issue, but seeing as it was directly in line of sight of this PR, just bundled it all up)
5. Fixed an inconsistency where some resources were not getting optimized correctly
6. Add test cases

Was thinking of backporting this to 0.30.x line, but due to the nature of these changes, will withhold this to the 0.31.x line

Documentation

N / A

TODO

1. remove demo code