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/dashboard/src/components/data-grid/data-grid.tsx

@@ -0,0 +1,41 @@
+import { FieldValues } from "react-hook-form"
+
+import {
+  DataGridBooleanCell,
+  DataGridCurrencyCell,
+  DataGridNumberCell,
+  DataGridReadOnlyCell,
+  DataGridRoot,
+  DataGridSkeleton,
+  DataGridTextCell,
+  type DataGridRootProps,
+} from "./components"
+
+interface DataGridProps<TData, TFieldValues extends FieldValues = FieldValues>
+  extends DataGridRootProps<TData, TFieldValues> {
+  isLoading?: boolean
+}
+
+const _DataGrid = <TData, TFieldValues extends FieldValues = FieldValues>({
+  isLoading,
+  ...props
+}: DataGridProps<TData, TFieldValues>) => {
+  return isLoading ? (
+    <DataGridSkeleton
+      columns={props.columns}
+      rows={
+        props.data?.length && props.data.length > 0 ? props.data.length : 10
+      }
+    />
+  ) : (
+    <DataGridRoot {...props} />
+  )
+}
+
+export const DataGrid = Object.assign(_DataGrid, {
+  BooleanCell: DataGridBooleanCell,
+  TextCell: DataGridTextCell,
+  NumberCell: DataGridNumberCell,
+  CurrencyCell: DataGridCurrencyCell,
+  ReadonlyCell: DataGridReadOnlyCell,
+})