Remove image block align none control

[aduth]

Closes #545

This pull request seeks to remove the "Align None" image control. The image controls already behave as toggles, so unsetting alignment back to "none" is a matter of clicking the selected option once more.

Before	After

Testing instructions:

Verify that there is no "Align None" option shown in the controls toolbar when selecting an image block, and that you can still restore the "none" alignment by toggling any active alignment.

[BE-Webdesign]

Looks good to me. Merge? Is there any reason why originally align-none was introduced in the WP Editor? I tried to search for its introduction in trac but was unable to find any context in the ticket https://core.trac.wordpress.org/ticket/30147. Seems it was added for accessibility?

[aduth]

Is there any reason why originally align-none was introduced in the WP Editor? I tried to search for its introduction in trac but was unable to find any context in the ticket https://core.trac.wordpress.org/ticket/30147. Seems it was added for accessibility?

Good find on context. cc @iseulde @azaozz @afercia having been involved in the original discussion. To the point of accessibility, so long as the toolbar can be navigated with a keyboard and the alignment buttons behave as a toggle, I don't really see the need for a standalone "None" control? Unless it's difficult to make clear the behavior of the toggle as resetting back to None.