Refactor argument validation utilities

[btjanaka]

Description

Currently, the argument validation utilities do not perform preprocessing on the arguments passed into them. However, every call of these utilities is prefaced with preprocessing (e.g., converting with asarray). This PR moves the preprocessing into the utilities. This should make it easier to handle argument validation as there is no longer a need to repeat preprocessing code.

TODO

• [x] Refactor validate_batch_args
• [x] Refactor validate_single_args

Questions

Status

• [x] I have read the guidelines in CONTRIBUTING.md
• [x] I have formatted my code using yapf
• [x] I have tested my code by running pytest
• [x] I have linted my code with pylint
• [x] I have added a one-line description of my change to the changelog in HISTORY.md
• [x] This PR is ready to go