Improve check for statements-only postfix templates

Before this change the check was quite complicated
because of cases like:
for (i in 1..9)
    foo(i)<caret>

It's not located in a block, but in the same time it's a stament.
So we had a tricky heuristics that if is parent is not a block, then
we should check if element isn't used as expression.

Of course this heuristics is wrong, e.g. for import/package nodes.

The solution is to reuse similar logic from BasicExpressionTypingVisitor.
it has been checked once that statement container is one of:
- KtBlockExpression
- KtContainerNodeForControlStructureBody
- KtWhenEntry

So there's no need to check anything else

 #KT-14986 Fixed
 #KT-14483 Fixed

idea/testData/codeInsight/postfix/tryInLocalClass.kt.after

@@ -0,0 +1,6 @@
+fun foo() {
+    class A {
+        // it's not a statement, while it has a block expression as an ancestor
+        val w = 1.try   <caret>
+    }
+}