fix(core): esbuild with cjs, fixes #115

[JamesKyburz]

Description

The previous output of core was esm, but as the file is .js and no type module or exports are present in package.json both require and import fail.

Changing the format to cjs fixes the issue, the size of dist isn't any larger. That said if we're using esbuild with sourcemaps we could minify to get a much smaller payload?

I chose cjs instead of esm + type module because the esm output from esbuild didn't work with lodash.

Motivation and Context

Fixes #115.

How Has This Been Tested?

Yes.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• I have added tests to cover my changes.
• All new and existing tests passed.