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/create-medusa-app/src/utils/process-manager.ts

@@ -4,7 +4,7 @@ type ProcessOptions = {
 }
 
 export default class ProcessManager {
-  intervals: NodeJS.Timer[] = []
+  intervals: NodeJS.Timeout[] = []
   static MAX_RETRIES = 3
 
   constructor() {
@@ -20,7 +20,7 @@ export default class ProcessManager {
     process.on("SIGINT", () => fn())
   }
 
-  addInterval(interval: NodeJS.Timer) {
+  addInterval(interval: NodeJS.Timeout) {
     this.intervals.push(interval)
   }