There is some behavior change regarding the new WrapWithSafeLetCall quickfix
1. it now works correctly on binary expressions by wrapping it with `()`
2. it now looks for a nullable position upward and do the modification there,
if possible. For example, consider the following code
```
fun bar(s: String): String = s
fun test(s: String?) {
bar(bar(bar(<caret>s)))
}
```
After applying this fix, FE1.0 yields
```
bar(bar(s?.let { bar(it) }))
```
while the new implementation yields
```
s?.let { bar(bar(bar(it))) }
```
This behavior aligns with FE1.0 if `bar` accepts nullable values.
Hash code can be no more used because in 1.3 we have nullable extension.
This fixes two wrap with safe let call tests and
one surround with null check test.
Ilya Kirillov