FIR: Fix false-positive ILLEGAL_RESTRICTED_SUSPENDING_FUNCTION_CALL on invokeExtension calls

compiler/testData/diagnostics/testsWithStdLib/coroutines/restrictSuspension/invokeExtension.kt

@@ -0,0 +1,18 @@
+// FIR_IDENTICAL
+// SKIP_TXT
+import kotlin.coroutines.RestrictsSuspension
+
+@RestrictsSuspension
+interface Scope
+
+suspend fun Scope.foo(
+    a1: suspend Scope.() -> Unit,
+    a2: suspend () -> Unit,
+    a3: suspend String.() -> Unit,
+) {
+    a1()
+    this.a1()
+    <!ILLEGAL_RESTRICTED_SUSPENDING_FUNCTION_CALL!>a2<!>()
+
+    "".<!ILLEGAL_RESTRICTED_SUSPENDING_FUNCTION_CALL!>a3<!>()
+}