mesh-build-node: push each done bundle to the artifact store from its own process and answer its reference (issue 1587, S5-S8, ADR 0498 §1 §2, lead decision L9)

After the build ended the module pushes the packed bundle with mesh-sdk's PushBlob under
<module>/<artifact> by its digest, a candidate's as a trunk build's, and the step answers
artifact-store://<module>/<artifact>/blobs/<digest> instead of the archive's path. A push
that fails fails the step not stored: <artifact>: <the store's words>; the packed bytes are
never written to the node. The manifest requires artifact-store and places its address.

modules/mesh-build-node/module.json

@@ -33,7 +33,8 @@
   "requires": [
     "forge-account",
     "npm-package-registry",
-    "node-toolchain"
+    "node-toolchain",
+    "artifact-store"
   ],
   "contributes": {
     "npm-package-registry": {
@@ -122,6 +123,14 @@
       "mode": "0644",
       "template": "files/gitconfig"
     },
+    {
+      "id": "registry",
+      "type": "file",
+      "path": "${dir:state}/registry",
+      "owner": "mesh-build-node",
+      "mode": "0644",
+      "template": "files/registry"
+    },
     {
       "id": "toolchain-dir",
       "type": "archive",