Inconsistent Value for Left Alignment in Toolbar's Alignment Button

[yhs-2551]

Hello react-quill maintainers,

I'm writing to report an observation I made regarding the values assigned to the alignment options in the toolbar. Specifically, when using the alignment button, the values returned for center alignment are "center", right alignment is "right", and justify alignment is "justify". However, the value for left alignment is consistently false rather than the expected "left".

This inconsistency caused some unexpected behavior when I was customizing the toolbar and required some additional debugging time to resolve. While I eventually overcame the issue, the discrepancy between the expected and actual value for left alignment did cause some friction in development.

I understand that the current implementation might be intentional. However, I'd like to suggest that changing the left alignment value to "left" could improve the overall developer experience and reduce confusion when implementing custom toolbar functionalities. Having a consistent naming convention for all alignment values can contribute to a more intuitive and user-friendly library.

I appreciate your consideration of this feedback. Thank you for your work on react-quill!

And Happy New Year to you all!