feat: update grade summary to show floating point grades

[KristinAoki]

Description

This PR resolves the bug that shows assignment's weighted grades that do not sum to the correct total grade. When a learner's weighted grades round down to the nearest whole number, but the summation of the weighted grades will round to a higher percent than the pre-rounded summation. To clarify this for users, the assignment's weighted grade will now show 2 decimal points, matching the legacy display found in the grade graph. To further clarify the difference, a tooltip was added to show the learner the raw weighted grade and the rounded weighted grade.

Before

After

Supportive Information

JIRA Ticket: AU-740

Handful of reports from both learners and partners regarding grade discrepancies between the final grade displayed in the grade summary and the sum of assignment type weighted grades listed in the grade summary.

There is a problem in the grading logic, where rounding occurs too soon (at interim steps instead of only at the end) and/or happens incorrectly.

Testing

1. Add graded assignments to a course
2. Click through the course and complete the graded assignments
3. View the progress page to see the grades
4. Confirm that the assignment's weighted grades are floating point numbers
5. Confirm that their sum when rounded equals the total
6. Hover over the tooltip in the table footer
7. Confirm that the raw grade matches the rum of the floating point percentages

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.85%. Comparing base (4a80532) to head (b128f16).

Files with missing lines	Patch %	Lines
...ess-tab/grades/grade-summary/GradeSummaryTable.jsx	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1558      +/-   ##
==========================================
+ Coverage   89.82%   89.85%   +0.03%     
==========================================
  Files         326      326              
  Lines        5601     5611      +10     
  Branches     1396     1394       -2     
==========================================
+ Hits         5031     5042      +11     
+ Misses        554      553       -1     
  Partials       16       16              

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