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/metadata-section/index.ts

@@ -0,0 +1 @@
+export * from "./metadata-section"

packages/admin/dashboard/src/components/common/metadata-section/metadata-section.tsx

@@ -0,0 +1,49 @@
+import { ArrowUpRightOnBox } from "@medusajs/icons"
+import { Badge, Container, Heading, IconButton } from "@medusajs/ui"
+import { useTranslation } from "react-i18next"
+import { Link } from "react-router-dom"
+
+type MetadataSectionProps<TData extends object> = {
+  data: TData
+  href?: string
+}
+
+export const MetadataSection = <TData extends object>({
+  data,
+  href = "metadata/edit",
+}: MetadataSectionProps<TData>) => {
+  const { t } = useTranslation()
+
+  if (!data) {
+    return null
+  }
+
+  if (!("metadata" in data)) {
+    return null
+  }
+
+  const numberOfKeys = data.metadata ? Object.keys(data.metadata).length : 0
+
+  return (
+    <Container className="flex items-center justify-between">
+      <div className="flex items-center gap-x-3">
+        <Heading level="h2">{t("metadata.header")}</Heading>
+        <Badge size="2xsmall" rounded="full">
+          {t("metadata.numberOfKeys", {
+            count: numberOfKeys,
+          })}
+        </Badge>
+      </div>
+      <IconButton
+        size="small"
+        variant="transparent"
+        className="text-ui-fg-muted hover:text-ui-fg-subtle"
+        asChild
+      >
+        <Link to={href}>
+          <ArrowUpRightOnBox />
+        </Link>
+      </IconButton>
+    </Container>
+  )
+}