deploy: add build using epics-in-docker musl image.

musl allows us to produce a fully static binary, which can be deployed
on almost any machine.

The intended deployment directory is /opt/rffe-epics-ioc, so that's
where we build the IOC, to guarantee that envPaths has the correct
definitions.

docker-compose.yml

@@ -0,0 +1,9 @@
+services:
+  build-static-ioc:
+    image: ghcr.io/cnpem/lnls-alpine-3.18-epics-7:v0.11.0
+    volumes:
+      - type: bind
+        source: ./
+        target: /opt/rffe-epics-ioc
+    working_dir: /opt/rffe-epics-ioc
+    command: lnls-build-static-ioc rffe-epics-ioc