FIR IDE: quickfix for WrapWithSafeLetCall

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.

core/compiler.common/src/org/jetbrains/kotlin/name/Name.java

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.name;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 public final class Name implements Comparable<Name> {
     @NotNull
@@ -85,6 +86,12 @@ public final class Name implements Comparable<Name> {
         }
     }
 
+    @Nullable
+    public String getIdentifierOrNullIfSpecial() {
+        if (special) return null;
+        return asString();
+    }
+
     @Override
     public String toString() {
         return name;