Support Go-to-Definition and hover on template names in `{ @macro template_name }`

(This was originally posted at https://github.com/flutter/flutter-intellij/issues/7203. I copied over since I can't seem to transfer from there.)

Many times we are looking at some widget's source-code and we find something like this:

```dart
/// {@macro flutter.services.TextInputConfiguration.enableIMEPersonalizedLearning}
final bool enableIMEPersonalizedLearning;
```

I can go to the variable and hit the shortcut for showing the definition, which in turn will pull the macro text, but I wanted to hit F4 and go to the macro definition itself, so I can read it as code, and not in the small doc pop-up window.

No file, test, or entry point is named. Start by locating the analyzer or IDE handling for dartdoc macro references such as {@macro flutter.services.TextInputConfiguration.enableIMEPersonalizedLearning}; done means Go-to-Definition opens the macro definition and hover shows its information.

Written by the indexing model from the issue text.