Allow orders create to take string

[kevinlacaille]

Allow planet orders create to take text as an input.

Example:

planet orders create {"name": "test_order", "products": [{"item_ids": ["20200922_183724_23_106a", "20200922_183722_17_106a"], "item_type": "PSScene4Band", "product_bundle": "analytic"}]}

Blocked by #519