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/invokeOverload2.kt

@@ -0,0 +1,9 @@
+fun foo() {
+    val x = fun(s: String) {}
+
+    fun nested() {
+        val <!UNUSED_VARIABLE!>x<!> = fun(i: Int) {}
+
+        x(10)
+    }
+}