Don't force public variables to use Hungarian notation (#8774)

People generally have expressed a dislike for the Hungarian notation
used in member variables, especially in examples/templates, and our
styleguide shouldn't be forced on downstream consumers, so this removes
all Hungarian notation from the examples/templates.

There are _some_ benefits to Hungarian for private member variables
(like knowing what's a member vs. local in a PR review) so we'll keep
private member variables the same for now, but public variables should
no longer use Hungarian notation, since it looks much worse. A new PMD
XPath rule has been added to accomplish this goal. Some other
non-compliant variables were fixed for the new rule.

styleguide/checkstyle.xml

@@ -168,12 +168,6 @@ module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
       <message key="name.invalidPattern"
         value="Type name ''{0}'' must match pattern ''{1}''." />
     </module>
-    <module name="MemberName">
-      <property name="format"
-        value="^(m_([a-zA-Z]|[a-z][a-zA-Z0-9]+)|value)$" />
-      <message key="name.invalidPattern"
-        value="Member name ''{0}'' must match pattern ''{1}''." />
-    </module>
     <module name="ParameterName">
       <property name="format"
         value="^([a-zA-Z]|[a-z][a-zA-Z0-9]+)$" />