Display better information in the component tree when you come across a `unknownTemplateOnlyComponent`

Now that people are using GJS by default, and we are using GJS for route templates the display of the components in the component tree isn't very useful

Having literally anything displayed here would be better, like a file path or something 🤷

Edit: It turns out that the screenshot above is what a vite app displays, in a classic app it just shows ``

Start by reproducing the component tree behavior for a GJS route template in a Vite app, then compare it with the classic app behavior described in the issue. Identify where unknownTemplateOnlyComponent entries are displayed; done means the tree shows a useful identifier such as a file path instead of an unhelpful blank entry or .

Written by the indexing model from the issue text.