fix(build): add english-only build

[henrymyers]

Description

As mentioned by @jeetiss in issue 786, the effects tab doesn't work when importing the english-only version of uploadcare-widget (because they import and patch different bundles).

This PR does the following:

• Generate an english-only bundle that imports the correct uploadcare.lang.en.js bundle. (ESM and UMD)
• Generate a minified english-only bundle that imports the correct uploadcare.lang.en.min.js bundle. (UMD)
• Update the existing minified bundle so that it imports the correct uploadcare.min.js bundle. (UMD)

I also did the equivalent for the @uploadcare/react-widget repo. See PR 252.

Checklist

• ~[ ] Tests (if applicable)~
• [x] Documentation (if applicable)
• [x] Changelog stub (or use conventional commit messages)

[nd0ut]

@henrymyers Thanks! I'll release it soon. 🚀