Reduce method visibility when possible

Reduce method visibility for package private classes when possible.

In the case of abstract classes that will eventually be made public,
the class has been made public and a package-private constructor has
been added.

Issue gh-8945

taglibs/src/test/java/org/springframework/security/taglibs/authz/AuthenticationTagTests.java

@@ -144,7 +144,7 @@ public class AuthenticationTagTests {
 
 		String lastMessage = null;
 
-		public String getLastMessage() {
+		String getLastMessage() {
 			return this.lastMessage;
 		}