GuessManagerImpl: support type constrains from DFA, various improvements

Partially fixes IDEA-181794 Suggest completion items with type casts in stream chains if there exists 'filter(x -> x instanceof Foo)' call
Fixes IDEA-182455 Code completion: resolve actual value type assigned to local variable

java/java-tests/testData/codeInsight/completion/normal/OptionalDfa.java

@@ -0,0 +1,8 @@
+import java.util.*;
+
+class Foo {
+    void test(Optional<Object> opt) {
+        opt.filter(x -> x instanceof String)
+          .map(s -> s.subst<caret>)
+    }
+}