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/button-menu/button-menu.tsx

@@ -0,0 +1,96 @@
+import { DropdownMenu, clx } from "@medusajs/ui"
+
+import { PropsWithChildren, ReactNode } from "react"
+import { Link } from "react-router-dom"
+
+type Action = {
+  icon: ReactNode
+  label: string
+  disabled?: boolean
+} & (
+  | {
+      to: string
+      onClick?: never
+    }
+  | {
+      onClick: () => void
+      to?: never
+    }
+)
+
+type ActionGroup = {
+  actions: Action[]
+}
+
+type ActionMenuProps = {
+  groups: ActionGroup[]
+}
+
+export const ButtonMenu = ({
+  groups,
+  children,
+}: PropsWithChildren<ActionMenuProps>) => {
+  return (
+    <DropdownMenu>
+      <DropdownMenu.Trigger asChild>{children}</DropdownMenu.Trigger>
+      <DropdownMenu.Content>
+        {groups.map((group, index) => {
+          if (!group.actions.length) {
+            return null
+          }
+
+          const isLast = index === groups.length - 1
+
+          return (
+            <DropdownMenu.Group key={index}>
+              {group.actions.map((action, index) => {
+                if (action.onClick) {
+                  return (
+                    <DropdownMenu.Item
+                      disabled={action.disabled}
+                      key={index}
+                      onClick={(e) => {
+                        e.stopPropagation()
+                        action.onClick()
+                      }}
+                      className={clx(
+                        "[&_svg]:text-ui-fg-subtle flex items-center gap-x-2",
+                        {
+                          "[&_svg]:text-ui-fg-disabled": action.disabled,
+                        }
+                      )}
+                    >
+                      {action.icon}
+                      <span>{action.label}</span>
+                    </DropdownMenu.Item>
+                  )
+                }
+
+                return (
+                  <div key={index}>
+                    <DropdownMenu.Item
+                      className={clx(
+                        "[&_svg]:text-ui-fg-subtle flex items-center gap-x-2",
+                        {
+                          "[&_svg]:text-ui-fg-disabled": action.disabled,
+                        }
+                      )}
+                      asChild
+                      disabled={action.disabled}
+                    >
+                      <Link to={action.to} onClick={(e) => e.stopPropagation()}>
+                        {action.icon}
+                        <span>{action.label}</span>
+                      </Link>
+                    </DropdownMenu.Item>
+                  </div>
+                )
+              })}
+              {!isLast && <DropdownMenu.Separator />}
+            </DropdownMenu.Group>
+          )
+        })}
+      </DropdownMenu.Content>
+    </DropdownMenu>
+  )
+}

packages/admin/dashboard/src/components/common/button-menu/index.ts

@@ -0,0 +1 @@
+export * from "./action-menu"