Hot Reload compatibility

[n12o]

Hot Reload replaces Unity Auto Refresh with faster incremental compilations. Since Auto Refresh handles asset updates, like shaders, Hot Reload also implements Asset Refresh functionality.

One of the users who uses both assets shared a problem:

The problem is that it also pushes a full refresh of ASE shaders, and I think only ASE shaders, when play starts. You can repro this simply by having ASE and A-impostor in an empty project as well as samples.

Hot Reload listens to file system events with a file watcher (dotnet/watchman). If a file changes, we import it using Unity API (AssetDatabase.ImportAsset). You can put a log into the HandleAssetChange method in the asset code to detect when the issue happens.