meson: adjust nlohmann-json dependency

Simplify the meson dependency for nlohmann-json, use the consistent
dependency name, and align the wrap file name with other repositories.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I3a682a3e07e38d0a1bfe35858e24f1bb74b4ec34
diff --git a/subprojects/nlohmann_json.wrap b/subprojects/nlohmann_json.wrap
new file mode 100644
index 0000000..3745380
--- /dev/null
+++ b/subprojects/nlohmann_json.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+revision = HEAD
+url = https://github.com/nlohmann/json.git
+
+[provide]
+nlohmann_json = nlohmann_json_dep