This method is used to generate headers for embedding files into the binary
(think about the new `#embed` feature in C23 and C++26).
While the stringification step itself was plenty fast, it then proceeded
to wrap everything using the `textwrap` module. `textwrap` is *very*
slow, as it's apparently optimized for human text.
This patch reimplements the wrapping logic using a simple regex,
resulting in a tremendous speed improvement (~6x), and switches to `map`
for the stringification itself (thanks Rémi!)
It also removes a (practically) unused argument, `initial_indent`.
The generated files are pretty much the same, with a tiny difference in
line length (for some reason the old logic overshot the requested line
length)