(Java) RamseteCommand putData causes crash if data is read before initialize() called

[fixermark]

Describe the bug
At this line (https://github.com/wpilibsuite/allwpilib/blob/main/wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/RamseteCommand.java#L218), leftVelocity is configured with a data-putter that assumes m_prevSpeeds exists.

m_prevSpeeds is not given a value until initialize() is called (https://github.com/wpilibsuite/allwpilib/blob/main/wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/RamseteCommand.java#L140).

If the command is added to SmartDashboard before the command is run, it crashes on attempting to dereference a null m_prevSpeeds reference.

To Reproduce

1. Create a new RamseteCommand.
2. Add the created command to the dashboard (SmartDashboard.putData("ramsete command", ramseteCommand);) before the command is run.

Expected behavior
Command's watched data is put on the dashboard.

Observed behavior
Program crashes at RamseteCommand.java:218

Screenshots
N/A

Desktop (please complete the following information):

• WPILib Version: 2023.3.2
• OS: Windows 11
• Java version: OpenJDK 17.0.5

Additional context
None