fix: remove events.js from core module (#650)

Optimization to `@openfeature/core` package. Both server and web need
the node-js `Events` interfaces, but obviously only the web needs them
poly-filled (they come with node).

This PR:

- marks `events.js` as an external dep in `@openfeature/core` meaning it
won't be bundled there (see esbuild
[doc](https://esbuild.github.io/api/#external))

This means that now `@openfeature/core` no longer includes `events.js`
(an un-needed polyfill for the server). The bundling pictured below only
happens in the `dist/` of `@openfeature/web-sdk`, and no longer in
`@openfeature/core` :


![image](https://github.com/open-feature/js-sdk/assets/25272906/2cfdce09-7f00-42a7-b797-9570c816cadb)

I've tested both the server and web SDKs based on this change locally in
the js-contribs by running the e2e test suite.

Relates to: #616

Signed-off-by: Todd Baert <[email protected]>

Author: toddbaert

packages/shared/package.json

@@ -19,8 +19,8 @@
     "lint": "eslint ./",
     "clean": "shx rm -rf ./dist",
     "type": "tsc --project ./tsconfig.json --declaration --emitDeclarationOnly",
-    "build:esm": "esbuild src/index.ts --bundle --sourcemap --target=es2016 --format=esm --outfile=./dist/esm/index.js --analyze",
-    "build:cjs": "esbuild src/index.ts --bundle --sourcemap --target=es2016 --format=cjs --outfile=./dist/cjs/index.js --analyze",
+    "build:esm": "esbuild src/index.ts --bundle --external:events --sourcemap --target=es2016 --format=esm --outfile=./dist/esm/index.js --analyze",
+    "build:cjs": "esbuild src/index.ts --bundle --external:events --sourcemap --target=es2016 --format=cjs --outfile=./dist/cjs/index.js --analyze",
     "build:rollup-types": "rollup -c ../../rollup.config.mjs",
     "build": "npm run clean && npm run build:esm && npm run build:cjs && npm run build:rollup-types",
     "postbuild": "shx cp ./../../package.esm.json ./dist/esm/package.json",