Typst: align array is too verbose

[vincentarelbundock]

One row of alignment array per cell is not great. Currently, the mechanism to overwrite defaults does not quite work, because style_tt() is called on a column-by-column sequence, rather than altogether, so we don't overwrite the defaults.

The Typst function to set alignment should also check the default array and not print the alignement array if it matches the default.