bug#48139: Add csv-field-alignment-toggle

[積丹尼 Dan Jacobson]

Regarding
C-c C-a         csv-align-fields
C-c C-u         csv-unalign-fields
actually it would be great if there was a toggle too,
so one needn't remember two keys.

Also one needn't have to look at the screen,
and think "Is the state I am looking at called aligned, or unaligned?"
And then think "If I am looking at unaligned, then I need to press c-c
c-A, and if I am looking at...

Or need to try both commands an stop at success.