[Secretkeeper] In-memory KeyValueStore

We introduce InMemoryStore, an implementation of KeyValueStore trait.
This can be used for implementing backends that VTS can run against.

Bug: 291224769
Test: atest VtsSecretkeeperTargetTest
Change-Id: Id109ee3bd38ec0979953b6285019c97d418172ef
diff --git a/security/secretkeeper/default/Android.bp b/security/secretkeeper/default/Android.bp
index 6612ea2..08cc67a 100644
--- a/security/secretkeeper/default/Android.bp
+++ b/security/secretkeeper/default/Android.bp
@@ -35,6 +35,7 @@
         "libauthgraph_hal",
         "libbinder_rs",
         "liblog_rust",
+        "libsecretkeeper_comm_nostd",
         "libsecretkeeper_core_nostd",
         "libsecretkeeper_hal",
     ],