FIR IDE: add shortcut to check if a KtSymbol is deprecated

core/compiler.common/src/org/jetbrains/kotlin/descriptors/Deprecation.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.descriptors
+
+data class Deprecation(
+    val level: DeprecationLevelValue,
+    val inheritable: Boolean,
+    val message: String? = null
+) : Comparable<Deprecation> {
+    override fun compareTo(other: Deprecation): Int {
+        val lr = level.compareTo(other.level)
+        //to prefer inheritable deprecation
+        return if (lr == 0 && !inheritable && other.inheritable) 1
+        else lr
+    }
+}
+
+/**
+ * This corresponds to [DeprecationLevel] in Kotlin standard library. A symbol annotated with [java.lang.Deprecated] is considered a
+ * warning.
+ */
+enum class DeprecationLevelValue {
+    WARNING, ERROR, HIDDEN
+}