meson: simplify dependencies

Leverage wrapfile `[provide]` directives to simplify the dependency
searching in the meson.build.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ia696d865d344ecc105fc7fb009c8419f8727ee02
diff --git a/subprojects/nlohmann-json.wrap b/subprojects/nlohmann-json.wrap
index 9096612..dbe7d46 100644
--- a/subprojects/nlohmann-json.wrap
+++ b/subprojects/nlohmann-json.wrap
@@ -1,3 +1,6 @@
 [wrap-git]
 url = https://github.com/nlohmann/json.git
 revision = HEAD
+
+[provide]
+nlohmann_json = nlohmann_json_dep