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: Id8a0909445b38271c0cdea79bad0ca9198cf7f0a
diff --git a/subprojects/nlohmann_json.wrap b/subprojects/nlohmann_json.wrap
index 0ba9c03..477e844 100644
--- a/subprojects/nlohmann_json.wrap
+++ b/subprojects/nlohmann_json.wrap
@@ -1,3 +1,6 @@
 [wrap-git]
 url = https://github.com/nlohmann/json
 revision = HEAD
+
+[provide]
+nlohmann_json = nlohmann_json_dep