Add Unity UI as dependency

Some projects don't have Unity UI added by default, resulting in.

```Assembly 'Packages/com.handzlikchris.fastscriptreload/Plugins/ImmersiveVrToolsCommon/ImmersiveVRTools.Common.Runtime.dll' will not be loaded due to errors:
Unable to resolve reference 'UnityEngine.UI'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.
```

So we should simply add it to the dependencies

Inspect the Unity package manifest and dependency configuration first, since the issue does not name a specific file. Confirm how Unity UI is currently declared, add the missing dependency, and verify that the reported UnityEngine.UI reference error no longer appears for projects that lack Unity UI by default.

Scritto dal modello di indicizzazione a partire dal testo della issue.