FIR IDE: Do not show hint from ImportQuickFix if the PSI have changed

Without this check, the import hint will be available even after the
quickfix is applied; this happens because the element to which the
quickfix is attached is not invalidated by the quickfix execution

Since the quickfix is still considered as available some time after
the import have been added, the hint is also generated. And the hint
stays even after the quickfix itself is discarded

`isOutdated` function prevents this

idea/idea-fir/src/org/jetbrains/kotlin/idea/quickfix/fixes/ImportQuickFix.kt

@@ -16,6 +16,7 @@ import com.intellij.openapi.ui.popup.JBPopupFactory
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiFile
 import com.intellij.psi.search.GlobalSearchScope
+import com.intellij.psi.util.PsiModificationTracker
 import org.jetbrains.kotlin.idea.KotlinBundle
 import org.jetbrains.kotlin.idea.caches.project.getModuleInfo
 import org.jetbrains.kotlin.idea.fir.api.fixes.diagnosticFixFactory
@@ -79,6 +80,21 @@ internal class ImportQuickFix(
         return true
     }
 
+    private val modificationCountOnCreate: Long = PsiModificationTracker.SERVICE.getInstance(element.project).modificationCount
+
+    /**
+     * This is a safe-guard against showing hint after the quickfix have been applied.
+     *
+     * Inspired by the org.jetbrains.kotlin.idea.quickfix.ImportFixBase.isOutdated
+     */
+    private fun isOutdated(project: Project): Boolean {
+        return modificationCountOnCreate != PsiModificationTracker.SERVICE.getInstance(project).modificationCount
+    }
+
+    override fun isAvailableImpl(project: Project, editor: Editor?, file: PsiFile): Boolean {
+        return super.isAvailableImpl(project, editor, file) && !isOutdated(project)
+    }
+
     private class ImportQuestionAction(
         private val project: Project,
         private val editor: Editor,