KT-64832 [FIR] Add more testData for invoke on local variables

Covers:
- suspend functional local variables
- overloads
- custom types with invoke operator

compiler/fir/analysis-tests/testData/resolve/extendedCheckers/unused/invokeSuspend.kt

@@ -0,0 +1,5 @@
+suspend fun foo(action: suspend () -> Unit) {
+    val <!UNUSED_VARIABLE!>x<!> = action
+
+    x()
+}