feat(admin-sdk,admin-bundler,admin-shared,medusa): Restructure admin packages (#8988)

**What**
- Renames /admin-next -> /admin
- Renames @medusajs/admin-sdk -> @medusajs/admin-bundler
- Creates a new package called @medusajs/admin-sdk that will hold all tooling relevant to creating admin extensions. This is currently `defineRouteConfig` and `defineWidgetConfig`, but will eventually also export methods for adding custom fields, register translation, etc. 
  - cc: @shahednasser we should update the examples in the docs so these functions are imported from `@medusajs/admin-sdk`. People will also need to install the package in their project, as it's no longer a transient dependency.
  - cc: @olivermrbl we might want to publish a changelog when this is merged, as it is a breaking change, and will require people to import the `defineXConfig` from the new package instead of `@medusajs/admin-shared`.
- Updates CODEOWNERS so /admin packages does not require a review from the UI team.

packages/admin/admin-vite-plugin/src/babel.ts

@@ -0,0 +1,32 @@
+import { parse, type ParseResult, type ParserOptions } from "@babel/parser"
+import _traverse, { type NodePath } from "@babel/traverse"
+import {
+  ExportDefaultDeclaration,
+  ExportNamedDeclaration,
+  File,
+  ObjectProperty,
+} from "@babel/types"
+
+/**
+ * Depending on whether we are running the CJS or ESM build of the plugin, we
+ * need to import the default export of the `@babel/traverse` package in
+ * different ways.
+ */
+let traverse: typeof _traverse
+
+if (typeof _traverse === "function") {
+  traverse = _traverse
+} else {
+  traverse = (_traverse as any).default
+}
+
+export { parse, traverse }
+export type {
+  ExportDefaultDeclaration,
+  ExportNamedDeclaration,
+  File,
+  NodePath,
+  ObjectProperty,
+  ParseResult,
+  ParserOptions,
+}