feat(dashboard,types,js-sdk,ui): Add missing Price List features (#7856)

**What**
- Adds missing features to Price List domain
- Adds `StackedFocusModal` and `StackedDrawer` components that should replace SplitView across the project.
- Add Footer to FocusModal
- Adds missing js-sdk functions and types

**Note**
The DatePickers in the PriceLists forms do not work as intended atm. The component is broken, and needs to be fixed. I am working on a fix, but choose to move that work into a separate branch, to prevent this PR from getting bigger then it already is. Will update once the fixes have been merged.

packages/medusa/src/api/admin/price-lists/validators.ts

@@ -55,8 +55,8 @@ export type AdminUpdatePriceListPriceType = z.infer<
 export const AdminCreatePriceList = z.object({
   title: z.string(),
   description: z.string(),
-  starts_at: z.union([z.string(), z.null()]).nullish(),
-  ends_at: z.union([z.string(), z.null()]).nullish(),
+  starts_at: z.string().nullish(),
+  ends_at: z.string().nullish(),
   status: z.nativeEnum(PriceListStatus).optional(),
   type: z.nativeEnum(PriceListType).optional(),
   rules: z.record(z.string(), z.array(z.string())).optional(),