meson: add missing dependencies and wraps

There were a number of headers used by the repository that were
missing explicit dependency information in the `meson.build`.  Add
these (CLI11, cereal, nlohmann-json) and the corresponding meson
wrap files so that the whole project can be built freestanding.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib54d18bc81690450116391fecdce996048f6ab39
diff --git a/subprojects/nlohmann-json.wrap b/subprojects/nlohmann-json.wrap
new file mode 100644
index 0000000..9096612
--- /dev/null
+++ b/subprojects/nlohmann-json.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://github.com/nlohmann/json.git
+revision = HEAD