feat(nix/binify): add binify

Create a store path where the executable `exe` is linked to
$out/bin/${name}. This is useful for e.g. including it as a “package”
in `buildInputs` of a shell.nix.

For example, if I have the exeutable /nix/store/…-hello, I can make it
into /nix/store/…-binify-hello/bin/hello with
`binify { exe = …; name = "hello" }`.

Change-Id: I600bdcd8f143bca2dd8dfbb165a9a5a8d6397622
Reviewed-on: https://cl.tvl.fyi/c/depot/+/624
Reviewed-by: tazjin <mail@tazj.in>

third_party/default.nix

@@ -115,6 +115,7 @@ let
       rsync
       runCommand
       runCommandNoCC
+      runCommandLocal
       rustPlatform
       rustc
       sbcl