mass replace "flip map -> foreach"

See `foreach`-introduction commit.
```
rg 'flip map ' --files-with-matches | xargs sed -i 's/flip map /foreach /g'
```

nixos/lib/build-vms.nix

@@ -54,11 +54,11 @@ rec {
 
       machinesNumbered = zipLists machines (range 1 254);
 
-      nodes_ = flip map machinesNumbered (m: nameValuePair m.fst
+      nodes_ = foreach machinesNumbered (m: nameValuePair m.fst
         [ ( { config, nodes, ... }:
             let
               interfacesNumbered = zipLists config.virtualisation.vlans (range 1 255);
-              interfaces = flip map interfacesNumbered ({ fst, snd }:
+              interfaces = foreach interfacesNumbered ({ fst, snd }:
                 nameValuePair "eth${toString snd}" { ipv4.addresses =
                   [ { address = "192.168.${toString fst}.${toString m.snd}";
                       prefixLength = 24;
@@ -88,7 +88,7 @@ rec {
                          "${config.networking.hostName}\n"));
 
                   virtualisation.qemu.options =
-                    flip map interfacesNumbered
+                    foreach interfacesNumbered
                       ({ fst, snd }: qemuNICFlags snd fst m.snd);
                 };
             }