Add explicit file extensions to module imports

[hawkticehurst]

Link to relevant issue

This pull request resolves #432
This pull request resolves #435

Description of changes

Fixes an ESM related bug caused by a lack of explicit file extensions (i.e. import file versus import file.js) in module imports.

[hawkticehurst]

Note: I have temporarily removed the CI/CD pipelines related to building and deploying our Storybook docs as I've discovered the changes in this PR will break Storybook builds.

Our current Storybook configuration requires a CommonJS-based module system to run and this PR changes the toolkit to use an ESM-based system.

Removing CI/CD pipelines means the current version of the docs should remain for the time being and allow me to merge this PR before I head out for vacation next week.

cc @daviddossett @kkbrooks I think we should revisit how we think about docs in the new year because I've wanted to switch out Storybook for something else for a while and this might be the right time to do so.

[kkbrooks]

@daviddossett @hawkticehurst I'll grab some time for us to chat about documentation in the New Year 😊