fix(build): Add types: and default: entries to exports['./core']

In the 'blockly/core' export:

- Replace the browser: entrypoint with a default: one.
- Add a types: entrypoint for core.

package.json

@@ -61,8 +61,9 @@
       "default": "./index.js"
     },
     "./core": {
-      "browser": "./blockly_compressed.js",
-      "node": "./core-node.js"
+      "types": "./core.d.ts",
+      "node": "./core-node.js",
+      "default": "./blockly_compressed.js"
     },
     "./blocks": {
       "types": "./blocks.d.ts",