Update python tester to allow a requirements file

[rickychen174]

Changes:

• Change the Python autotester settings schema to include an optional field for a requirements file
• The Python autotester setup will find the requirements file from the test files and install those packages

Testing Procedure

• Rebuild schema and enter a Python assignment. The Python environment section will have a new field: Package requirements file
• Add a requirements file with NumPy and add a test file which uses NumPy.
• Save the settings and run tests
  • With the correct requirements file name provided, the NumPy test passes
  • With an incorrect requirements file name provided, the tests do not start
  • With no requirements file name provided, the NumPy test fails

[david-yz-liu]

@rickychen174 nice work! Please also make these changes for the jupyter tester.

[donny-wong]

@rickychen174 nice work! Please also make these changes for the jupyter tester.

@rickychen174, please also add it to the pyta tester, thank you.

[rickychen174]

@rickychen174 nice work! Please also make these changes for the jupyter tester.

I applied the changes for the jupyter and pyta testers.

[david-yz-liu]

Nice work, @rickychen174!