pw_kvs: Simple debug command line interface

Add the pw_kvs:debug_cli executable for performing very basic manual
testing locally.

Change-Id: Ifab6eb237f92a1b09ed7e3797485f9889e6cec64
diff --git a/pw_kvs/BUILD b/pw_kvs/BUILD
index 93d9bfd..cb9464b 100644
--- a/pw_kvs/BUILD
+++ b/pw_kvs/BUILD
@@ -91,3 +91,14 @@
         "//pw_log",
     ],
 )
+
+cc_binary(
+    name = "debug_cli",
+    srcs = ["debug_cli.cc"],
+    copts = ["-std=c++17"],
+    deps = [
+        ":crc16",
+        ":in_memory_fake_flash",
+        ":pw_kvs",
+    ],
+)