[Feature] Drop .left and .right attributes from DriveBase

[laurensvalk]

Is your feature request related to a problem? Please describe.
The DriveBase class has two undocumented attributes called left and right which can be used to access the motor objects with which the drive base was initialized.

Describe the solution you'd like
Delete them. They are not needed and not documented.

On Move Hub, this means we can drop the custom attribute handler for this class and save a bit more space.

[laurensvalk]

Maybe we can add an topic: optimization label for things like this.

[laurensvalk]

Similar note: We can save 136 bytes by allowing just one DriveBase instance on Move Hub instead of 2.