Remove duplicate resolveFile methods

Both org.apache.maven.cli.MavenCli and org.apache.maven.cli.configuration.SettingsXmlConfigurationProcessor contain identical package-private static methods called resolveFile - they can be replaced with the new public class org.apache.maven.cli.ResolveFile with the single public static method resolveFile. Also it would be more appropriate to rename workingDirectory parameter to baseDirectory.