Upgrade SDK to hybrid esm/cjs module

[tiagosiebler]

Summary

• Upgrade SDK to hybrid ESM/CJS module
• Upgrade dev dependencies (jest & related)
• Move webpack dependencies to optional
• Deprecate barrel exports

Additional Information

• There's no real workflow/code change within the SDK. Largely just changes to how imports behave within and outside the SDK.
• Normal usage should remain unchanged, no breaking changes are expected, since the package.json should automatically map existing implementations to the correct modules within the SDK.

PR Checklist

As part of the PR, make sure you have:

• No breaking changes / documented all breaking changes clearly.
• Updated & checked that all tests pass.
• Updated the endpoint map (optional, if you know how).
• Increased the version number in the package.json
• Checked npm install runs without issue.
• Included the package-lock.json, if it changed after npm install
• Checked npm run build runs without issue.