Create Python API for VideoEncoder

[Dan-Flores]

This PR creates a simple VideoEncoder class, and updates several tests to utilize the VideoEncoder.to_file pattern.

• test_bad_input_parameterized is the VideoEncoder equivalent to the AudioEncoder test that ensures general error checking occurs, while test_bad_input tests method specific errors.

• test_contiguity: is the VideoEncoder equivalent to the AudioEncoder test to ensure contiguous and non-contiguous tensors can be encoded, and are encoded equivalently.