Support suspend conversion in callable reference adaptation

#KT-15917 In Progress

compiler/testData/diagnostics/tests/suspendConversion/basicSuspendConversionForCallableReference.kt

@@ -0,0 +1,18 @@
+// !LANGUAGE: +SuspendConversion
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo1(f: suspend () -> Unit) {}
+fun bar1() {}
+
+fun <T> foo2(e: T, f: suspend (T) -> Unit) {}
+fun bar2(x: Int) {}
+fun bar2(s: String) {}
+
+fun test() {
+    foo1(::bar1)
+
+    foo2(42, ::bar2)
+    foo2("str", ::bar2)
+
+    foo2(42, <!TYPE_MISMATCH!>::bar1<!>)
+}