Handle existing apps for deep links

[micahmo]

This PR enhances the obtainium://add... deep linking functionality. I found that if I followed a link for an app that I already had installed, it still prompted me to add it again. This PR improves that functionality so that, if the app that the user is trying to "add" is already installed, we navigate to the existing app page instead of the add app page.

Before

qemu-system-x86_64_rMOD8QS6Vv.mp4

After

qemu-system-x86_64_SkvLsRPh7y.mp4

[ImranR98]

The current functionality seems more useful to me since the user might want to replace their existing config with the new one (I know I've done this before). But I can see how that would be confusing if it wasn't their intention. Maybe we should have a confirmation box to let the user either overwrite their current config or not.

[micahmo]

The current functionality seems more useful to me since the user might want to replace their existing config with the new one

Ok fair enough, I hadn't considered that work flow!

How about we still navigate to "add" by default, but if the same app URL is already installed, we show a snackbar that tells the user and lets them navigate to the app page. If you think that approach would work I can try it out.

[ImranR98]

Oh hold on, this is about obtainium://add which just takes you to the add app page, not obtainium://app which is what I was thinking of (that imports a whole pre-built app config). Should've paid more attention. For add I think your proposal makes sense as is.

[micahmo]

How about we still navigate to "add" by default, but if the same app URL is already installed, we show a snackbar that tells the user and lets them navigate to the app page.

Here's what this approach would look like, if you want to consider this instead.

main...micahmo:feature/improve-deep-links-2

qemu-system-x86_64_lSD0PpypbG.mp4