[FIR] Introduce FirResolvable

FirResolvable is an interface representates fir node wit calleeReference
It will be useful for infer `try` and `when` expressions as function call

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirQualifiedAccess.kt

@@ -5,13 +5,10 @@
 
 package org.jetbrains.kotlin.fir.expressions
 
-import org.jetbrains.kotlin.fir.FirReference
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
 import org.jetbrains.kotlin.fir.visitors.FirVisitor
 
-interface FirQualifiedAccess : FirStatement {
-    val calleeReference: FirReference
-
+interface FirQualifiedAccess : FirResolvable {
     val safe: Boolean get() = false
 
     val explicitReceiver: FirExpression? get() = null

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirResolvable.kt

@@ -0,0 +1,12 @@
+/*
+ * Copyright 2010-2019 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.fir.expressions
+
+import org.jetbrains.kotlin.fir.FirReference
+
+interface FirResolvable : FirStatement {
+    val calleeReference: FirReference
+}