[FE 1.0] Support suspend only SAM conversions

^KT-50477 Fixed

compiler/testData/diagnostics/tests/samConversions/kt50477.kt

@@ -0,0 +1,23 @@
+// !LANGUAGE: -SuspendOnlySamConversions
+
+fun interface FI {
+    suspend fun call() // suspending now(!!!)
+}
+
+fun accept(fi: FI): Int = TODO()
+
+suspend fun foo() {}
+fun foo2() {}
+
+fun main() {
+    val fi: suspend () -> Unit = {} // Lambda of a suspending(!!!) functional type
+    accept(<!TYPE_MISMATCH!>fi<!>) // ERROR: Type mismatch. Required: FI Found: suspend () → Unit
+
+    accept(::foo)
+    val x1 = ::foo
+    accept(<!TYPE_MISMATCH!>x1<!>) // ERROR: Type mismatch. Required: FI Found: suspend () → Unit
+
+    accept(::foo2)
+    val x2 = ::foo2
+    accept(x2)
+}