Improve handling of speed and corresponding driving state

What's Changed

• Improve handling of speed and corresponding driving state by @pnbruckner in #99

  • Maintain driving state even when not updating speed sensor
    Bug fix: When updates come too close together, speed sensor is not updated. However, if speed was previously above set driving speed threshold, still need to keep device_tracker state as driving, which was previously not the case.

  • Add time to hold driving state after speed falls below configured driving speed
    New config option: Can help avoid undesired state changes when, e.g., slowing to go around a corner or when stopping at an intersection.

  • Add max time between speed sensor updates
    New config option: If set, will clear speed sensor state when exceeded.

Full Changelog: 3.5.0...3.6.0