feat!: update default main file output for design tokens (#8299)

**Related Issue:** n/a

## Summary

Engineers prefer to use es6 to import specific tokens when necessary.
The es6 format (which is tree-shakable) should be the one imported by
default.

BREAKING CHANGE:

- `import * as tokens from "@esri/calcite-design-tokens";` now imports a
tree-shakable list of design tokens in camelCase format rather than a
JSON object.

packages/calcite-design-tokens/package.json

@@ -9,8 +9,8 @@
     "tokens"
   ],
   "type": "module",
-  "main": "./dist/js/global.js",
-  "types": "./dist/js/global.d.ts",
+  "main": "./dist/es6/global.js",
+  "types": "./dist/es6/global.d.ts",
   "files": [
     "./dist/**/*"
   ],