dashed and dotted hlines have uneven spacing

[Enivex]

[PgBiel]

The problem here is that lines are broken down into one line (cell border) for each cell they span:

https://github.com/PgBiel/typst-tablex/blob/3a45350240e997165cc1be3520173f6d6ea3723f/tablex.typ#L1505-L1512

This could be fixed by changing the line breaking algorithm. Changing the algorithm is also necessary to fix #27.