[epilogue] Add missing docs (#6844)

epilogue-runtime/src/main/java/edu/wpi/first/epilogue/EpilogueConfiguration.java

@@ -40,4 +40,7 @@ public class EpilogueConfiguration {
    * string.
    */
   public String root = "Robot";
+
+  /** Default constructor. */
+  public EpilogueConfiguration() {}
 }

epilogue-runtime/src/main/java/edu/wpi/first/epilogue/logging/NullLogger.java

@@ -8,6 +8,9 @@ import edu.wpi.first.util.struct.Struct;
 
 /** Null data logger implementation that logs nothing. */
 public class NullLogger implements DataLogger {
+  /** Default constructor. */
+  public NullLogger() {}
+
   @Override
   public DataLogger getSubLogger(String path) {
     // Since a sublogger would still log nothing and has no state, we can just return the same

epilogue-runtime/src/main/java/edu/wpi/first/epilogue/logging/errors/CrashOnError.java

@@ -12,6 +12,9 @@ import edu.wpi.first.epilogue.logging.ClassSpecificLogger;
  * code.
  */
 public class CrashOnError implements ErrorHandler {
+  /** Default constructor. */
+  public CrashOnError() {}
+
   @Override
   public void handle(Throwable exception, ClassSpecificLogger<?> logger) {
     throw new RuntimeException(

epilogue-runtime/src/main/java/edu/wpi/first/epilogue/logging/errors/ErrorPrinter.java

@@ -8,6 +8,9 @@ import edu.wpi.first.epilogue.logging.ClassSpecificLogger;
 
 /** An error handler implementation that prints error information to the console. */
 public class ErrorPrinter implements ErrorHandler {
+  /** Default constructor. */
+  public ErrorPrinter() {}
+
   @Override
   public void handle(Throwable exception, ClassSpecificLogger<?> logger) {
     System.err.println(