Add a meson option to enable googletest

This adds infrastructure to enable and support unit tests using
googletest.

Tested:
Confirmed that the option correctly enables googletest.

Signed-off-by: Jason M. Bills <jason.m.bills@linux.intel.com>
Change-Id: I8a93305391cc69b607ce5e22390f3140455e66e0
diff --git a/subprojects/googletest.wrap b/subprojects/googletest.wrap
new file mode 100644
index 0000000..0d37d2e
--- /dev/null
+++ b/subprojects/googletest.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://github.com/google/googletest
+revision = HEAD
\ No newline at end of file