Add new enum Type in vehicle classification for stand-up scooters

[schmidtlorenz]

feat(vehicle classifications): add classification for stand-up scooters, motivated by possible NCAP target type

#### Reference to a related issue in the repository refers to issue #673

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This adds a new enum Type in vehicle classification for stand-up or kickboard scooters.

Take this checklist as orientation for yourself, if this PR is ready for the Change Control Board:

• [/] My suggestion follows the style and contributors guidelines.
• [/] I have taken care about the message documentation and the fields and enums documentation.
• [/] I have done the DCO signoff.
• [ ] My changes generate no errors when passing CI tests.
• [ ] I have successfully implemented and tested my fix/feature locally.
• [ ] Appropriate reviewer(s) are assigned.

[jdsika]

Please fix build in order to hand this over to the CCB. Can you add the reference to a relevant NCAP document? Maybe even in the description. I think most descriptions would benefit from a little more verbose comments.

[ThomasNaderBMW]

Jobs are failing because of this: osi_object.proto:871:36: "osi3.MovingObject.VehicleClassification.TYPE_STANDUP_SCOOTER" uses the same enum value as "osi3.MovingObject.VehicleClassification.TYPE_SEMITRACTOR". If this is intended, set 'option allow_alias = true;' to the enum definition.

So Semitractor has already ID 16, you can take 17 e.g. @schmidtlorenz

[schmidtlorenz]

I removed the links since I could not find persistent versions (e.g. PURL or DOI).