[commands] Add StartRun command factory (#6572)

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/Commands.java

@@ -93,6 +93,19 @@ public final class Commands {
         () -> {}, run, interrupted -> end.run(), () -> false, requirements);
   }
 
+  /**
+   * Constructs a command that runs an action once, and then runs an action every iteration until
+   * interrupted.
+   *
+   * @param start the action to run on start
+   * @param run the action to run every iteration
+   * @param requirements subsystems the action requires
+   * @return the command
+   */
+  public static Command startRun(Runnable start, Runnable run, Subsystem... requirements) {
+    return new FunctionalCommand(start, run, interrupted -> {}, () -> false, requirements);
+  }
+
   /**
    * Constructs a command that prints a message and finishes.
    *

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/Subsystem.java

@@ -146,6 +146,18 @@ public interface Subsystem {
     return Commands.runEnd(run, end, this);
   }
 
+  /**
+   * Constructs a command that runs an action once and then runs another action every iteration
+   * until interrupted. Requires this subsystem.
+   *
+   * @param start the action to run on start
+   * @param run the action to run every iteration
+   * @return the command
+   */
+  default Command startRun(Runnable start, Runnable run) {
+    return Commands.startRun(start, run, this);
+  }
+
   /**
    * Constructs a {@link DeferredCommand} with the provided supplier. This subsystem is added as a
    * requirement.