[FEATURE ADD] Create priority queue for video encoding #13

Describe the feature that is being tested/implemented
Create a priority queue of what files to encode first.

• Prioritize completing all encodes for a single reference file before moving on to the other reference files.
• Prioritize hardware encoders first, as they are typically faster than software encoders, which would create the bigger chunk of files first.
• Prioritize completing all VMAF score calculations for a single reference file before moving on to the other reference files.
• Prioritize completing all VMAF plotting for a single reference file before moving on to the other reference files.

List any relations to other issues in this repository or in other repositories
N/A