fix: fix sonarcloud maintainability phase 3

[vvatanabe]

• fix the code smell warnings in tests
• fix the code smell warnings in MatchFactory
• fix the code smell warnings in Match
• fix the code smell warnings in L33tSubDict
• fix the code smell warnings in KeyboardLoader
• fix the code smell warnings in Keyboard
• fix the code smell warnings in ClasspathResource
• fix the code smell warnings in Pattern

[coveralls]

coverage: 92.454% (-0.06%) from 92.509% when pulling c77f699 on fix-sonarcloud-maintainability-3 into a4f95da on main.