Give a container the names, rather than a resolver to ask

The commit before this said "told where to resolve names" and passed --dns,
which is not what it ended up doing. This is that correction: a container is
given the names themselves, written into its own hosts file by the runtime.

The reason for the change is the decision the mesh already made about names — a
file rather than a resolver, because it works on every runtime, needs no
package and has no failure mode of its own. Passing a resolver address would
have required a resolver to exist, which at that point none did.

A resolver is coming, for the case a file genuinely cannot express: a service
named under a machine, postgres.novox.internal, where the wildcard cannot be
enumerated in advance. When it arrives it will need this field back under its
own name. It is not being kept in the meantime — a field nothing fills is a
field nobody can trust, and the vocabulary is asserted by a count for exactly
that reason.

internal/apply/apply.go

@@ -812,12 +812,12 @@ func applyContainer(ctx context.Context, r *declaration.Container, run Runner) (
 	for _, v := range r.Volumes {
 		args = append(args, "--volume", v)
 	}
-	for _, n := range r.Nameservers {
-		// Per container rather than by changing the machine's resolver configuration. That file
-		// belongs to something else on most machines, and a host that edited it would be fighting
-		// whatever owns it on every boot — the fault this host exists to avoid, in the one place
-		// it would be hardest to see.
-		args = append(args, "--dns", n)
+	for _, h := range r.Hosts {
+		// Written into the container's own hosts file by the runtime. Per container rather than
+		// by editing the machine's resolver configuration: that file belongs to something else on
+		// most machines, and a host that edited it would be fighting whatever owns it on every
+		// boot — the fault this host exists to avoid, in the place it would be hardest to see.
+		args = append(args, "--add-host", h)
 	}
 	args = append(args, r.Image)
 	args = append(args, r.Args...)