Modify mobile keyboard to be scrollable

[Johnwz123]

Description

Closes #2872

Modified mobile keyboard key selection. Previously, users had to click a button to cycle through rows of different sets of keys. Now, users scroll horizontally through a single row containing every key.

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [ ] Code quality improvements

How to test

1. Access Source Academy either on a physical mobile device or use browser dev tools to shrink viewport dimensions to access mobile UI.
2. Go to the Source Academy Playground page and expand the draggable keyboard on the right side of the screen.
3. Attempt typing characters into the editor by scrolling to find and clicking the respective keys. Ensure key click is not registered while scrolling. (Note: Editor needs to be in focus (blinking cursor) to be able to type.)

Checklist

• [x] I have tested this code
• [ ] I have updated the documentation

[coveralls]

Pull Request Test Coverage Report for Build 8649923586

Details

• 0 of 31 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.04%) to 35.229%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/commons/mobileWorkspace/MobileKeyboard.tsx	0	31	0.0%
<!--	Total:	0	31	0.0%	-->

Totals
Change from base Build 8636747271:	-0.04%
Covered Lines:	5199
Relevant Lines:	13793

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💛 - Coveralls