chore: move next admin packages to core repo (#5983)

**What**
- Move packages for `next` version of admin to core repo

**Other**
- Since this PR introduces packages that depend on Vite 5, it also introduces @types/node@^20. We have never had a direct dependency on the types package for Node, and as far as I can see that has resulted in us using the types from Node.js@8, as those are a dependency of one of our dependencies. With the introduction of @types/node@^20, two of our packages had TS errors because they were using the NodeJS.Timer type, which was deprecated in Node.js@14. We should add specific @types/node packages to all our packages, but I haven't done so in this PR to keep it as clean as possible.
- Q: @olivermrbl I've added the new packages to the ignore list for changeset, is this enough to prevent them from being published?

packages/admin-next/dashboard/tailwind.config.cjs

@@ -0,0 +1,29 @@
+import preset from "@medusajs/ui-preset";
+import path from "path";
+
+const rootProject = path.join(
+  process.cwd(),
+  "../../apps/server/src/admin/**/*.{js,jsx,ts,tsx}"
+);
+
+// get the path of the dependency "@medusajs/ui"
+const medusaUI = path.join(
+  path.dirname(require.resolve("@medusajs/ui")),
+  "**/*.{js,jsx,ts,tsx}"
+);
+
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+  presets: [preset],
+  content: [
+    "./index.html",
+    "./src/**/*.{js,ts,jsx,tsx}",
+    medusaUI,
+    rootProject,
+  ],
+  darkMode: "class",
+  theme: {
+    extend: {},
+  },
+  plugins: [],
+};