Feature/224 add accessibility to the label

[farassadek]

This PR related to the course planner ticket https://github.com/seas-computing/course-planner/issues/224 Based on the conversion with Vittorio, the invisible label should be accessible by the screen reader. Therefore the dispaly: none in the Label component in mark-one should be replaced with this css found in this url https://accessibility.18f.gov/hidden-content/

Types of changes

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

Checklist:

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

[codecov[bot]]

Codecov Report

Merging #81 (1543ac0) into develop (4cabc64) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop      #81   +/-   ##
========================================
  Coverage    98.24%   98.24%           
========================================
  Files           42       42           
  Lines          513      514    +1     
  Branches        96       96           
========================================
+ Hits           504      505    +1     
  Misses           5        5           
  Partials         4        4           

Impacted Files	Coverage Δ
src/Forms/InputLabel.tsx	97.22% <100.00%> (+0.07%)	:arrow_up:

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