Convert the resolver from the module it replaces: forward, answer at 127.0.0.1, point the runtime at it

Read against hal/modules/dnsmasq-app (hal dnsmasq-app conversion, hq 08-connectivity).
On the machines it runs, the predecessor's dnsmasq answers every name: the mesh's own
itself, the rest forwarded to 1.1.1.1 and 8.8.8.8, its module's defaults; resolv.conf
names it alone at 127.0.0.1, and the container runtime's dns is the machine's tunnel
address, so the host and every container resolve the world through it. The nox module
forwarded nothing, listened on 127.0.0.55 — a convention of its own beside the one every
machine already followed — and read a machines file that the module's `facts` already
asks the mesh for, so taking it would have left an adopted machine with a resolv.conf
pointing at an address nothing answered on, and no upstream for anything else.

Now the resolver keeps `no-resolv` (the documented loop — finding its own address in
resolv.conf and becoming its own upstream — stays impossible) and forwards to the same
two explicit upstreams; listens on mesh0 and 127.0.0.1, which systemd-resolved does not
hold; requires `mesh-addressing`, since its data is the mesh's addresses; and writes the
runtime's `dns` into daemon.json beside whatever the machine had (ADR 0102), at this
machine's own address — `${machine:address}`, new in the controller. The runtime is not
restarted for it: it reads the key at start, not on reload, and a restart stops every
container; on the machine this replaces the value is already there.

resolv-conf names the resolver alone, as the predecessor's file did; its placeholder second
line was a fallback nothing ever reached. resolved-split-dns follows the address. The
mesh's suffix as a local domain comes with the machines file, so a mesh name the resolver
does not know is refused here rather than asked upstream. mDNS is not carried: no module
does it and the design says mesh names are not multicast names.

modules/resolv-conf/module.json

@@ -8,6 +8,6 @@
 
   "resources": [
     {"id": "resolv", "type": "file", "path": "/etc/resolv.conf", "mode": "0644",
-     "content": "# Managed by the mesh.\n#\n# For a machine where nothing else owns this file. On one where systemd-resolved\n# or NetworkManager does, assign that module instead — this one and those claim\n# the same thing, so the mesh refuses the pair rather than letting them take\n# turns overwriting each other, which is the failure this claim exists to stop.\n#\n# The mesh's resolver first, because it answers only the mesh's names and\n# forwards nothing: a query it does not recognise falls through to the next\n# line rather than being answered wrongly.\nnameserver 127.0.0.55\n\n# And what this machine used before. Replace this line with the resolver this\n# machine should use for everything that is not the mesh — it is not the mesh's\n# to choose, and a public one written here by default would send every query\n# this machine makes somewhere nobody agreed to.\nnameserver 127.0.0.53\n"}
+     "content": "# Managed by the mesh.\n#\n# For a machine where nothing else owns this file. On one where systemd-resolved\n# or NetworkManager does, assign that module instead — this one and those claim\n# the same thing, so the mesh refuses the pair rather than letting them take\n# turns overwriting each other, which is the failure this claim exists to stop.\n#\n# The mesh's resolver, and only it — the one line the predecessor wrote on every\n# machine it set up. It answers the mesh's names itself and forwards everything\n# else to upstreams named in its own configuration, never read from this file.\n# This file used to carry a second nameserver as a placeholder for \"whatever\n# this machine used before\"; that was never a fallback for names the mesh does\n# not know — a resolver's second line is asked only when the first does not\n# answer at all — and now that the first answers everything it would be a line\n# nothing ever reached.\nnameserver 127.0.0.1\noptions edns0\n"}
   ]
 }