Allow creating new templates from registry templates

## Context
This will allow the use of the templates on regsitry.coder.com to create a new template from within the Coder dashboard.

## Prerequisite(s)

- [x] #10639

## Design

An initial mockup by @bpmct is available in the RF document on Notion.
![template builder drawio](https://github.com/coder/coder/assets/10648092/cbed88bd-4555-4a9d-878d-bfff668e68f8)

