Initial pass on Antithesis testing

This adds a "limbo_stress" tool for stress testing Limbo in
non-deterministic way together with support code to run the tests under
Antithesis (which makes them deterministic). The stress tester does not
really do anything useful yet, this is just a step to make sure we can
run tests under Antithesis.

scripts/antithesis/launch.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+curl --fail -u "$ANTITHESIS_USER:$ANTITHESIS_PASSWD" \
+  -X POST https://$ANTITHESIS_TENANT.antithesis.com/api/v1/launch/basic_test \
+  -d "{\"params\": { \"antithesis.description\":\"basic_test on main\",
+      \"antithesis.duration\":\"1\",
+      \"antithesis.config_image\":\"$ANTITHESIS_DOCKER_REPO/limbo-config:antithesis-latest\",
+      \"antithesis.images\":\"$ANTITHESIS_DOCKER_REPO/limbo-workload:antithesis-latest\",
+      \"antithesis.report.recipients\":\"$ANTITHESIS_EMAIL\"
+      } }"