Prior to this change, builtins would take their arguments as `wchar_t **`.
This implies that the order of the arguments may be changed (which is
true, `wgetopter` does so) but also that the strings themselves may be
changed, which no builtin should do.
Switch them all to take `const wchar_t **` instead: now the arguments may
be rearranged but their contents may no longer be modified.
This runs build_tools/style.fish, which runs clang-format on C++, fish_indent on fish and (new) black on python.
If anything is wrong with the formatting, we should fix the tools, but automated formatting is worth it.
Now that the IWYU cleanup has been merged compile all, not just a couple, of
the builtin modules independent of builtin.cpp. That is, no longer `#include
builtin_NAME.cpp` in builtin.cpp. This is more consistent, more in line with
what developers expect, and is likely to reduce mistakes.
Reduces lint errors from 384 to 336 (-13%). Line count from 6307 to 4988 (-21%).
Another step in resolving issue #2902.
