Add diagnostics tests. Forbid callable reference to coroutineContext

#KT-16908: Fixed

compiler/testData/diagnostics/tests/coroutines/callableReference/invokeOutideSuspend.kt

@@ -0,0 +1,8 @@
+// !LANGUAGE: +Coroutines
+// SKIP_TXT
+
+import kotlin.reflect.KSuspendFunction0
+
+fun test(c: KSuspendFunction0<Unit>) {
+    <!ILLEGAL_SUSPEND_FUNCTION_CALL!>c<!>()
+}

compiler/testData/diagnostics/tests/coroutines/callableReference/outsideSuspend.kt

@@ -0,0 +1,6 @@
+// !LANGUAGE: +Coroutines
+// SKIP_TXT
+
+suspend fun foo() {}
+
+val ref = ::foo