buildomat: add basic build/test job mimicking the Actions workflow

.github/buildomat/jobs/build-and-test.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+#:
+#: name = "build-and-test / illumos"
+#: variety = "basic"
+#: target = "helios"
+#: rust_toolchain = "stable"
+#:
+
+set -o errexit
+set -o pipefail
+set -o xtrace
+
+rustc --version
+
+banner build
+ptime -m cargo build --tests --verbose
+
+banner test
+ptime -m cargo test --verbose