AA FIR: functional type for anonymous function

^KTIJ-17657 In progress

analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/anonymousFunction.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    val f = <expr>fun(it: String) {}</expr>
+}

analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/anonymousFunction.txt

@@ -0,0 +1,2 @@
+expression: fun(it: String) {}
+type: (kotlin.String) -> kotlin.Unit