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.

coderd/autostart/schedule/schedule.go

@@ -26,6 +26,7 @@ var defaultParser = cron.NewParser(parserFormatWeekly)
 //  local_sched, _ := schedule.Weekly("59 23 *")
 //  fmt.Println(sched.Next(time.Now().Format(time.RFC3339)))
 //  // Output: 2022-04-04T23:59:00Z
+//
 //  us_sched, _ := schedule.Weekly("CRON_TZ=US/Central 30 9 1-5")
 //  fmt.Println(sched.Next(time.Now()).Format(time.RFC3339))
 //  // Output: 2022-04-04T14:30:00Z