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/src/index.css

@@ -0,0 +1,33 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+@layer base {
+  @font-face {
+    font-family: "Inter";
+    font-weight: 400;
+    src: url("./assets/fonts/Inter-Regular.ttf") format("truetype");
+  }
+
+  @font-face {
+    font-family: "Inter";
+    font-weight: 500;
+    src: url("./assets/fonts/Inter-Medium.ttf") format("truetype");
+  }
+
+  @font-face {
+    font-family: "Roboto Mono";
+    font-weight: 400;
+    src: url("./assets/fonts/RobotoMono-Regular.ttf") format("truetype");
+  }
+
+  @font-face {
+    font-family: "Roboto Mono";
+    font-weight: 500;
+    src: url("./assets/fonts/RobotoMono-Medium.ttf") format("truetype");
+  }
+
+  :root {
+    @apply bg-ui-bg-subtle text-ui-fg-base;
+  }
+}