Render long code in multiple grids

[jneug]

For long source code with many page breaks, the alignment of line numbers can sometimes drift off and no longer match the code lines.

Right now, #sourcecode creates a grid with multiple columns.

To solve the issue, long code blocks could be split into multiple grids, to allow the alignment of line numbers to "reset" and prevent drift.

Problem with this approach:

• W don't know where to split the raw code without affecting syntax highlighting and access to the highlighted code is not possible (right now).

A solution could be to use the previous approach used in v0.0.5 to set the complete code in every grid, but to clip it to show only the appropriate lines.

[jneug]

With Typst 0.0.9 this should not be necessary any longer.