Fix ProcessAdapter deprecation warnings

[jwren]

Replaces deprecated ProcessAdapter with ProcessListener. Reduces deprecated API usages by 33 in 2025.2 (future-proofing for when check is enabled).

https://github.com/JetBrains/intellij-community/blob/master/platform/util/src/com/intellij/execution/process/ProcessAdapter.java

[pq]

Cool!

Here's a thought... ProcessAdapter was nice in that it avoided a bunch of boilerplate which this PR adds in. How about introducing our own ProcessAdapter so we can reap the benefits (without depending on deprecated API)? Maybe in io.flutter.utils?

[jwren]

I like the adapter pattern as well, but expectations are shifting under us here. This PR is almost free and moves our repo in a direction that will have it more accepted and green in the JB Marketplace.

Lets chat on VC, I can completely see both sides of the argument here, lets defer to the larger team.

[pq]

This PR is almost free

I think that's debatable given our time talking about it 😄 -- but it's all good! It's more than worth the time since it's a nice way to frame a larger and more important question about evolving coding standards.

My 2 cents is that while it may be free to add the boilerplate, we'll continue to pay the price in the ways we always have with unnecessary code (in the way of maintenance and understandability). I don't really see a shift here but I think it's an awesome conversation to have. Looking forward to it!