Add tests for converting expressions of function types to suspending functional types

compiler/testData/codegen/box/suspendConversion/overloadResolutionBySuspendModifier.kt

@@ -0,0 +1,19 @@
+// !LANGUAGE: +SuspendConversion
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(x: () -> Int) {}
+fun foo(x: suspend () -> Int) {}
+
+fun usualCall(): Int = 42
+suspend fun suspendCall(): Int = 42
+
+// candidate without suspend conversions is more specific
+fun test2(f: () -> Int, g: suspend () -> Int) {
+    foo(f)
+    foo(g)
+}
+
+fun box(): String {
+    test2({ 1 }, { 2 })
+    return "OK"
+}