Add positive grading to assessments

[victorhuangwq]

Description

Adds ability to do positive grading to assignments as well as the following sub-features:

• Warning when switching between positive and negative if there's currently an annotation
• Add an indication about whether it's positive or negative grading in the annotation box
• Add is_positive_grading to export assessments

Motivation and Context

Iliano requested the feature to be added as changing 122 rubrics from positive to negative has been difficult for their class.

How Has This Been Tested?

Grading style testing

Tested negative grading:

Tested positive grading:

Tested Annotations Warning

• Tested changing when there are annotations > warning shows
• Tested changing when there are no annotations > warning does not show

Tested Import & Export

• Turned on positive grading
• Export assessment and check yml
• Imported and checked that positive grading is one

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have run rubocop for style check. If you haven't, run overcommit --install && overcommit --sign to use pre-commit hook for linting
• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, included in this PR

Other issues / help required

If unsure, feel free to submit first and we'll help you along.

[victorhuangwq]

• Add warning when switching between positive and negative if there's annotation
• Add an indication about whether it's positive or negative grading

[victorhuangwq]

• Add is_positive_grading to export assessments

[damianhxy]

Functionally, works as expected

Left some comments, but otherwise lgtm!

[damianhxy]

LGTM!