Support hosting the Widget Previewer in Android Studio / Intellij

[bkonyi]

Initial support has landed in VSCode and looks like this:

https://github.com/user-attachments/assets/50a4d280-c15e-44e9-b063-e1b313ad7cb0

To match this, we need to be able to:

• Launch and manage the lifecycle of flutter widget-preview start --web-server.
• Open an iframe or browser within Intellij to view the preview application.
• Send IDE navigation events via the Editor DTD service to update which previews are visible based on the currently selected file.