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/common/user-link/index.ts

@@ -0,0 +1 @@
+export * from "./user-link"

packages/admin/dashboard/src/components/common/user-link/user-link.tsx

@@ -0,0 +1,34 @@
+import { Avatar, Text } from "@medusajs/ui"
+import { Link } from "react-router-dom"
+
+type UserLinkProps = {
+  id: string
+  first_name?: string | null
+  last_name?: string | null
+  email: string
+  type?: "customer" | "user"
+}
+
+export const UserLink = ({
+  id,
+  first_name,
+  last_name,
+  email,
+  type = "user",
+}: UserLinkProps) => {
+  const name = [first_name, last_name].filter(Boolean).join(" ")
+  const fallback = name ? name.slice(0, 1) : email.slice(0, 1)
+  const link = type === "user" ? `/settings/users/${id}` : `/customers/${id}`
+
+  return (
+    <Link
+      to={link}
+      className="flex items-center gap-x-2 w-fit transition-fg hover:text-ui-fg-subtle outline-none focus-visible:shadow-borders-focus rounded-md"
+    >
+      <Avatar size="2xsmall" fallback={fallback.toUpperCase()} />
+      <Text size="small" leading="compact" weight="regular">
+        {name || email}
+      </Text>
+    </Link>
+  )
+}