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/meson.options b/meson.options
index ed29e7b..2e05965 100644
--- a/meson.options
+++ b/meson.options
@@ -11,3 +11,10 @@
     value: 'disabled',
     description: 'Enable use of the Intel Crashdump service',
 )
+
+option(
+    'tests',
+    type: 'feature',
+    value: 'disabled',
+    description: 'Enable unit tests',
+)