CheckstyleConfigLoader does not support VisibilityModifier

https://checkstyle.sourceforge.io/apidocs/com/puppycrawl/tools/checkstyle/checks/design/VisibilityModifierCheck.html

<module name="VisibilityModifier">
    <property name="severity" value="${checkstyle.visibilitymodifier.severity}" default="error"/>
    <property name="packageAllowed" value="${checkstyle.visibilitymodifier.packageallowed}" default="false"/>
    <property name="protectedAllowed" value="${checkstyle.visibilitymodifier.protectedallowed}" default="false"/>
    <property name="publicMemberPattern" value="${checkstyle.visibilitymodifier.publicmemberpattern}" default="^serialVersionUID$"/>
    <property name="allowPublicFinalFields" value="${checkstyle.visibilitymodifier.allowpublicfinalfields}" default="true"/>
    <property name="allowPublicImmutableFields" value="${checkstyle.visibilitymodifier.allowpublicimmutablefields}" default="true"/>
    <property name="immutableClassCanonicalNames" value="${checkstyle.visibilitymodifier.immutableclasscanonicalnames}" default="java.lang.String, java.lang.Integer, java.lang.Byte, java.lang.Character, java.lang.Short, java.lang.Boolean, java.lang.Long, java.lang.Double, java.lang.Float, java.lang.StackTraceElement, java.math.BigInteger, java.math.BigDecimal, java.io.File, java.util.Locale, java.util.UUID, java.net.URL, java.net.URI, java.net.Inet4Address, java.net.Inet6Address, java.net.InetSocketAddress"/>
    <property name="ignoreAnnotationCanonicalNames" value="${checkstyle.visibilitymodifier.ignoreannotationcanonicalnames}" default="org.junit.Rule, org.junit.ClassRule, com.google.common.annotations.VisibleForTesting"/>
</module>

Start by locating CheckstyleConfigLoader and compare its supported configuration properties with the VisibilityModifierCheck documentation linked in the issue. Confirm the expected handling for the listed module properties, then add coverage for the configuration and verify that VisibilityModifier is loaded correctly.