Compose a node's own modules from their builds and read what providers elsewhere serve, so a self-composing node hands moved modules and settles served settings as the controller does (issue 1126)

frombus composed every module from the indexer's raw manifest: no moved module
was handed, so the node stood in for own secrets the vault leaves to the
provisioner (the seed's refusals on all four nodes), and a provider elsewhere
had no config values, so mailu's served domain refused shanks.

- takein: the controller's take-in of a done key (artifacts, launchers, the
  templates archive's texts, Resolve) as one SDK rule; catalogue.Launchers holds
  the launcher rule buildstep now delegates to.
- frombus: each module placed on the composing node, and each kept at another
  build (Scope.KeptAt, a fingerprint), composes from its built manifest; another
  node's modules give the keys their served values fill (Reader.Served).
- buscompose: Declared.Served and Principal.ServedReads grant every node the read
  of exactly those keys of mesh-config_resolved.
- compose.ArtifactStoreAddress: the store as the node's composition routes to it.

go/compose/frombus/testdata/catalogue-c05aa5e6-mesh-provisioner-client.module.json

@@ -0,0 +1,60 @@
+{
+  "module": "mesh-provisioner-client",
+  "version": "1",
+  "claims": [
+    {
+      "name": "node-provisioner",
+      "scope": "node"
+    }
+  ],
+  "own-secrets": {
+    "provisioner-broker": "${dir:state}/broker"
+  },
+  "secrets-owner": "mesh-provisioner-client",
+  "resources": [
+    {
+      "id": "account",
+      "type": "user",
+      "name": "mesh-provisioner-client",
+      "shell": "/usr/bin/nologin",
+      "home": "/var/lib/mesh-provisioner-client"
+    },
+    {
+      "id": "state",
+      "type": "directory",
+      "mode": "0700",
+      "owner": "mesh-provisioner-client",
+      "place": ".",
+      "unknown": "program"
+    },
+    {
+      "id": "client",
+      "type": "process",
+      "name": "mesh-provisioner-client",
+      "artifact": "client",
+      "run": [
+        "./mesh-provisioner-client"
+      ],
+      "env": {
+        "MESH_PROVISIONER_CREDENTIAL": "${dir:state}/broker",
+        "MESH_PROVISIONER_STATE": "${dir:state}"
+      },
+      "user": "mesh-provisioner-client",
+      "health": {
+        "kind": "unit"
+      }
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "client",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/mesh-provisioner-client",
+        "binary": "mesh-provisioner-client"
+      }
+    ]
+  }
+}