meson: adjust nlohmann-json dependency

- Simplify the dependency logic in the meson.build.
- Align the meson dep name with consistent practices from other repos.
- Use the non-versioned wrap file.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I0e3052763bffe9f98d8ca10c5b523b58e000f636
7 files changed