Add functionality for getting warp markers

[fizzy123]

Addresses this: https://github.com/leolabs/ableton-js/issues/60

Not sure if this is how much this meets your standards so if you have any requests feel free to let me know.

[what-the-diff[bot]]

• Added a new function get_warp_markers to Clip.py
• Updated the interface GettableProperties in clip.ts with warp markers

[leolabs]

Thank you for your PR, that looks perfect!