**Background:**
To help users explore templates and find the right one for their intended use, we will replace the close button with a back button in the TemplateDialog once a template has been selected from search results ({T272354}). This only applies when inserting a new template. With this ticket, we will also add a warning message that will warn users about data loss if they have entered data into a selected template.
**Requirements**
[] Implement behind feature flag with {T272354}
[] Add warning about data loss when clicking the back button after having added data.
[] Use #OOUI error state component from `OO.ui.ProcessDialog`
[] Title:"Go back?" Error message: "Going back will remove this template along with any information you have entered, returning you to the template selection window. This action is irreversible."
[] Button options: "Cancel" (normal button) and "Remove template." (primary, destructive button)
[] When no data has been entered, show no warning.
[] Ensure it works on mobile
**Mock**
{F34147437}
For reference, same specs as test instance (with .9 opacity white overlay), just different wording:{F32188591}
Related tickets:
- Prototyping ticket: {T260887}