feat: workspace view for schedules (#991)

Summary:

This adds the client-side implementation to match the types introduced
in #879 and #844 as well as a card in the Workspaces page to present
workspace the data.

Details:

* Added a convenient line break in the example schedule.Weekly
* Added missing `json:""` annotations in codersdk/workspaces.go
* Installed cronstrue for displaying human-friendly cron strings
* Adjusted/Added client-side types to match codersdk/workspaces.go
* Added new component WorkspaceSchedule.tsx

Next Steps:

The WorkspaceSchedule.tsx card only presents data (on purpose). In order
to make it PUT/modify data, a few changes will be made:

- a form for updating workspace schedule will be created
- the form will wrapped in a dialog or modal
- the WorkspaceSchedule card will have a way of opening the modal which
will likely be generalized up to WorkspaceSection.tsx

Impact:

This is user-facing

This does not fully resolve either #274 or #275 (I may further decompose
that work to reflect reality and keep things in small deliverable
increments), but adds significant progress towards both.

site/package.json

@@ -33,6 +33,7 @@
     "@xstate/inspect": "0.6.5",
     "@xstate/react": "3.0.0",
     "axios": "0.26.1",
+    "cronstrue": "2.2.0",
     "formik": "2.2.9",
     "history": "5.3.0",
     "react": "17.0.2",