Support SAM conversion in psi2ir

SAM conversion takes a function value (function type or a subtype),
and produces a SAM interface value.

compiler/testData/ir/irText/expressions/sam/samConstructors.kt

@@ -0,0 +1,7 @@
+// WITH_JDK
+fun test1() = Runnable { }
+
+fun test2(a: () -> Unit) = Runnable(a)
+
+fun foo() {}
+fun test3() = Runnable(::foo)