NPM-PACKAGE - Move to ESM

[deinok]

@baywet Getting clean ESM + CommonJS outputs without introducing bundling has been messy, so I went with this approach:

• Ship ESM only (removed the CommonJS build)
• Fixed a few JSON import issues
• Removed the JSON copy script (not needed since we import it directly)
• Moved some files under the lib/ folder
• Updated tsconfig.json to include lib/ instead of excluding everything else

The VSCode plugin should still work fine with ESM because it’s bundled with webpack, so webpack will bundle what it needs from the ESM module and tree-shake unused exports where possible.

Note: If this package is consumed outside the VSCode extension, switching to ESM-only may be a breaking change for environments still relying on CommonJS.

[baywet]

Thanks for the contribution!

I double checked and the other big consumer of this package is also using a bundler
https://github.com/OfficeDev/microsoft-365-agents-toolkit/blob/c0eb0bed661202bfd85b3bb1bd61e21b0b73c0b4/packages/fx-core/package.json#L87

[deinok]

@baywet I left two points unresolved. Also could you please trigger CI?

[baywet]

@baywet I left two points unresolved. Also could you please trigger CI?

done. Another aspect of cjs I forgot to mention earlier is jest's configuration that'll need to be updated.