Improve the bundle app download experience

[psobolewskiPhD]

🧰 Task

The main installation guide has a section for the bundled app:
https://napari.org/stable/tutorials/fundamentals/installation.html#install-as-a-bundled-app
There is also a more detailed guide:
https://napari.org/stable/tutorials/fundamentals/installation_bundle_conda.html

But neither of these provides the actual download link directly. They make you navigate to the Releases page, which is really annoying and confusing if there has been a pre-release recently.

We should provide direct links or tiles to the specific version of napari matching the docs version.
Note that we do this in the Quick Start:
https://napari.org/stable/tutorials/fundamentals/quick_start.html#installation