profiles: add unconfined balena-etcher profile

Balena Etcher runs in a degraded sandbox mode when unprivileged userns
is not available. Add an unconfined profile so it's properly
sandboxed.

Signed-off-by: Georgia Garcia <georgia.garcia@canonical.com>

profiles/apparmor.d/balena-etcher

@@ -0,0 +1,12 @@
+# This profile allows everything and only exists to give the
+# application a name instead of having the label "unconfined"
+
+abi <abi/4.0>,
+include <tunables/global>
+
+profile balena-etcher /usr/lib/balena-etcher/balena-etcher flags=(unconfined) {
+  userns,
+
+  # Site-specific additions and overrides. See local/README for details.
+  include if exists <local/balena-etcher>
+}