feat: add sideEffects configuration

Only /encoding.js export has side-effects, and those
side-effects are internal.

It is documented to load multi-byte codecs for both this import
and future /encoding-lite.js imports, even if the current import
does not use the provided TextDecoder.

This is because /encoding.js and /encoding-lite.js are designed
to return the exact same TextDecoder class and methods, and loading
full implementation provides multi-byte encodings support everywhere.

The usecase is that /encoding-lite.js can potentially be used as a
global polyfill, and the setup has to avoid polyfill conflicts if
something loads /encoding.js and then something else replaces it
with /encoding-lite.js

Author: ChALkeR

package.json

@@ -237,6 +237,9 @@
     "./fallback/platform.js": "./fallback/platform.native.js",
     "./fallback/utf8.auto.js": "./fallback/utf8.auto.native.js"
   },
+  "sideEffects": [
+    "./encoding.js"
+  ],
   "peerDependencies": {
     "@noble/hashes": "^1.8.0 || ^2.0.0"
   },