fix: Add tests for the various parsers and cover edge cases

[lbrooks]

List of updates to the method:

• Sanitize numbers to ensure within [0-255]
  • When called with isRgbw == false, numbers outside of [0-255[ could make it into the PaletteType[] returned
• When there aren't enough values to complete the last color, fill the missing values with 0s
  • In the previous code, the value would contain NaN
• Simplify logic
  • Switched from a reducer needing state to a simple for loop
• Add tests to cover all edge cases