docs: use vitepress config for markdown pre-renderer

[ST-DDT]

The api-pages.ts file is required during both the docs building and now api docs generation.
(Unfortunately, there is a circular dependency in there api-pages -> vitepress config -> markdown renderer -> api-docs generator -> api-pages, but that shouldn't be an issue, because the generator is indepent of the file's content)

We can either create it with dummy data if it is missing or just add it to the repo.

Adding the file to the repo has the added benefit, of making it easier to detect, if the docs generation does no longer generate all the modules.

[codecov]

Codecov Report

Merging #835 (c8937f3) into main (bb2dfb6) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #835   +/-   ##
=======================================
  Coverage   99.34%   99.34%           
=======================================
  Files        1921     1921           
  Lines      179170   179170           
  Branches      895      895           
=======================================
  Hits       177993   177993           
  Misses       1121     1121           
  Partials       56       56