Adding Yandex Shifts Motion Dataset

[stepankonev]

This PR add the support for the Yandex Shifts Motion Dataset

Known problems:

• Yandex Shifts Motion Dataset only supports center lines for path graph lanes.
• There are inconsistencies with car headings; they seem to be defined up to π. We've proposed a heuristic method in fix_headings to prevent flipping, which can be especially tricky for interpolated data. However, this method is not perfect.
• Multiple reads from the filesystem for same file.