Table & TableCell Components: Remove Table margin and add TableCell alignment prop

[natalynyu]

This PR removes the margin around the Table component, since the margin was causing a horizontal scrollbar to appear in Course Planning. The margin was moved to the PageBody component instead. Also, the prop alignment was added to the TableCell component so that users can adjust how the content within the td is positioned (text-align is set to left, right, or center). The default value of the alignment prop is left.

Types of changes

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

Checklist:

• [x] I have run eslint on the code
• [x] I have added JSDoc for all of my code (where applicable)
• [ ] I have added tests to cover my changes.

Priority:

• [x] Normal
• [ ] High

Related Issues:

Addresses #117

[codecov[bot]]

Codecov Report

Merging #43 into develop will not change coverage by %. The diff coverage is n/a.

@@            Coverage Diff            @@
##           develop       #43   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           21        21           
  Lines          222       228    +6     
  Branches        18        18           
=========================================
+ Hits           222       228    +6     

Impacted Files	Coverage Δ
src/Tables/TableCell.tsx	100.00% <0.00%> (ø)

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