lexy: new wrap

[Totto16]

This is a mostly header only project from here

It ports most features from cmake, but not all of these below:

• benchmarks: only one is comparison benchmark missing, since the benchmarks compare this parser framework to others, which not all are in the wrapdb, so "Boost.JSON" comparison is missing by choice (the wrap doesn't need that feature)
• tests: 2 tests are some complicated ones, that generate many things via cmake, they are not required imo, to use this as wrap

But it's usable since it ports everything needed

CI failure is related to the comments (discussion below)

[Totto16]

I noticed, that the wrap for doctest, which is only a clone of the upstream meson.build adds the dir "/doctest" to the include directories, but the CMake Defintion adds the root ("/") of the project as include directory, so this projects uses doctests includes like this:

#include <doctest/doctest.h>

which is perfectly valid with CMake, but meson fails, since it expects:

#include <doctest.h>

The best approach imo is to fix this upstream 8in doctest), but are there any other options, to fix this in a good way, if that wouldn't be possible (see doctest/doctest#792)
We can't patch (diff_files field) the upstream meson.build file here... 🤔

Fixing it in the lexy upstream isn't possible that easily, due to usage of cmake there, and I think, the discussion would be the same as in doctest/doctest#792 🤔

@eli-schwartz Any opinion on this, since you are the creator of doctest/doctest#670