GuessManagerImpl: box values on fast-path; disable DFA on primitive types at all

Fixes IDEA-189340 Does not show Number methods during auto completion

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

@@ -0,0 +1,6 @@
+class Foo {
+    void test() {
+        Number x = 10;
+        return x.lon<caret>
+    }
+}

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

@@ -0,0 +1,6 @@
+class Foo {
+    void test() {
+        Number x = 10;
+        return x.longValue()
+    }
+}