FIR IDE: Consolidate tests for AddExclExclFix in one directory.

I found these tests only _after_ the previous changes, so I needed to
merge and/or remove redundant tests.

idea/testData/quickfix/addExclExclCall/iterableGeneric.kt

@@ -0,0 +1,5 @@
+// "Add non-null asserted (!!) call" "true"
+fun <T: Collection<Int>?> foo(c: T) {
+    for (i in <caret>c) { }
+}
+