Cron Monitor Slug only Modifiable through API

### Problem Statement

I would like to edit my cron monitor's slug through the UI.
I created a new monitor without updating the title, so now my monitor slug is "new-monitor".
From what I have read, I will now need to use the Sentry API to update the monitor rather than just being able to update it through the frontend UI.

### Solution Brainstorm

Allow for the cron monitor slug to be modified through the UI.

### Product Area

Crons

Start from the cron monitor UI and trace how the monitor title and slug are currently displayed and saved. Check the existing API behavior for monitor updates before changing the form. Done means a user can edit the cron monitor slug in the UI and save the new value without using the API directly.

Written by the indexing model from the issue text.