Refine default postfix templates selector

There is new settings checkCanBeUsedAsValue
Also expression filtering are split into to parts:
- getNonFilteredExpressions is trivially goes until it reaches
first block body of some declarations
- all additional filtering is merged into Condition that is passed into
PostfixTemplateExpressionSelectorBase super-call

Notable changes for users:
- do not suggest try for non-top-level expressions
- do not suggest var/par/etc for loops

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

@@ -0,0 +1,3 @@
+fun foo(x: Boolean) {
+    foo(x.assert    <caret>)
+}