chore: migrate v3 as monorepo package, fix tests, update scripts, move to tsdown, fix exports

Signed-off-by: tunnckoCore <5038030+tunnckoCore@users.noreply.github.com>

Author: tunnckoCore

old-source/.editorconfig .editorconfigold-source/.editorconfig renamed to .editorconfig

@@ -3,6 +3,9 @@ packages/formidable-next/src/super-headers.js
 packages/formidable-next/src/super-readable-stream.js
 
 **/super-headers.js
+**/CHANGELOG.md
+**/fixture/**
+**/fixtures/**
 
 # because we use ESLint for most things - both linting and formatting (with ESLint Stylistic)
 **/*.{js,jsx,ts,tsx}

.prettierignore

@@ -3,7 +3,7 @@ import xaxa from 'eslint-config-xaxa';
 export default xaxa({
   ignores: [
     '**/super-headers.js',
-    '**/old-source/**',
+    '**/packages/formidable-v3/**',
     '**/*.cjs',
     'async-gens-with-queues-slow.ts',
   ],