**What**
- Revamps the DatePicker component.
- Addresses all issues with broken DatePickers across admin.
**Note**
- Part of this PR is adding a I18nProvider which is used to set the locale that is used for our DatePicker and Calendar components. Per default they use the browser locale. In the current implementation, we are grabbing the locale to use from the language that is picked in the "Profile" section. This means that currently the only possible locale is "en-US", meaning times uses AM/PM. This is likely not what we want, but we need to make a decision on how we want to handle this globally, will create a ticket for it and we can then clean it up later on.
- This PR does not include "presets" or a DateRange picker that were part of the old implementation. Will open tickets to re-add this later on, but since we aren't using it in admin any where it makes sense to address later.
- This PR also bumps and pin every `@radix-ui` dependency in `@medusajs/ui` and `@medusajs/dashboard`. Our different versions were pulling in multiple versions of internal radix dependencies which were breaking Popover and Dialog behaviour across admin. One thing to note is that Radix have started to print warnings for missing Descriptions and Titles in dialogs. We should add these as we go, for better accessibility. Its not an urgent task but something we can add as we clean up admin over the following weeks.
CLOSES CORE-2382
**What**
- Implements new Region domain design
- Adds new SplitView component for managing adding nested relations in FocusModals, eg. adding countries to a region.
- Adds new Combobox component for multi select fields in forms
**medusajs/ui**
- Fix styling of RadioGroup.Choicebox component
CLOSES CORE-1650, CORE-1671
**What**
- Move packages for `next` version of admin to core repo
**Other**
- Since this PR introduces packages that depend on Vite 5, it also introduces @types/node@^20. We have never had a direct dependency on the types package for Node, and as far as I can see that has resulted in us using the types from Node.js@8, as those are a dependency of one of our dependencies. With the introduction of @types/node@^20, two of our packages had TS errors because they were using the NodeJS.Timer type, which was deprecated in Node.js@14. We should add specific @types/node packages to all our packages, but I haven't done so in this PR to keep it as clean as possible.
- Q: @olivermrbl I've added the new packages to the ignore list for changeset, is this enough to prevent them from being published?
