add BatteryStates msg (backport #250)

[mergify]

This PR introduces a new message definition: BatteryStates.

• BatteryStates contains an array of sensor_msgs/msg/BatteryState messages.
• The purpose is to support broadcasting the status of multiple batteries from a single controller.
• This message will be used by the upcoming battery_state_broadcaster in ros2_controllers.

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This is an automatic backport of pull request #250 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 20d59df has failed:

On branch mergify/bp/jazzy/pr-250
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Changes to be committed:
	new file:   control_msgs/msg/BatteryStateArray.msg

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   control_msgs/CMakeLists.txt

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally