FIR. Refactor smart-cast representation in FIR tree

Make smart-casts non-transparent expression without delegation
to underlying FirQualifiedAccessExpression, as children delegation in
fir tree has unclear semantics
Remove two different kinds of tree nodes for smart-casts

analysis/analysis-api/testData/referenceResolve/smartCastExpression.kt

@@ -0,0 +1,9 @@
+interface Foo {
+    fun function()
+}
+
+fun foo(parameter: Any) {
+    if (parameter is Foo) {
+        <caret>parameter.function()
+    }
+}

analysis/analysis-api/testData/referenceResolve/smartCastExpression.txt

@@ -0,0 +1,2 @@
+Resolved to:
+0: parameter: kotlin.Any

analysis/analysis-api/testData/referenceResolve/smartCastInvokeReceiver.kt

@@ -0,0 +1,9 @@
+interface WithInvoke {
+    operator fun invoke() {}
+}
+
+fun foo(parameter: Any) {
+    if (parameter is WithInvoke) {
+        <caret>parameter()
+    }
+}

analysis/analysis-api/testData/referenceResolve/smartCastInvokeReceiver.txt

@@ -0,0 +1,2 @@
+Resolved to:
+0: parameter: kotlin.Any