devtools: fix sourcegraph

Permissions get mangled on container restart. This adds an init
container to fix them.

Change-Id: I37c44e23a75b8ec41e6aba2ed38eee223496b8b9
diff --git a/kube/mirko.libsonnet b/kube/mirko.libsonnet
index 134c785..5203afd 100644
--- a/kube/mirko.libsonnet
+++ b/kube/mirko.libsonnet
@@ -129,6 +129,7 @@
             nodeSelector: null,
             securityContext: {},
             container:: error "container(s) must be set",
+            initContainer:: null,
             ports:: {
                 publicHTTP: {}, // name -> { port: no, dns: fqdn }
                 grpc: { main: 4200 }, // name -> port no
@@ -189,6 +190,7 @@
                             },
                         } + cfg.volumes,
                         containers_: cfg.containers,
+                        [if cfg.initContainer != null then "initContainers"]: [cfg.initContainer],
                         nodeSelector: cfg.nodeSelector,
 
                         serviceAccountName: component.sa.metadata.name,