build: Add wrapfiles for dependencies

- Update meson.build and add wrapfiles so that all dependencies are
  handled as subprojects.

- This allows builds completely outside of bitbake or an SDK.
  refer: https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-virtual-sensor/+/42349

Tested: built ledManager repo successfully using `meson build`.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I35db603d4aa9c2eee41c3cfb27eba6953950fe44
diff --git a/subprojects/googletest.wrap b/subprojects/googletest.wrap
new file mode 100644
index 0000000..766a562
--- /dev/null
+++ b/subprojects/googletest.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://github.com/google/googletest.git
+revision = HEAD