feat(wpcarro/emacs): Package bag.el

More Elisp packaging :)

Change-Id: I4cf5695fd97ed922b8dfe698a168061042208c73
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6001
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

users/wpcarro/emacs/pkgs/bag/default.nix

@@ -0,0 +1,26 @@
+{ pkgs, depot, ... }:
+
+let
+  bag = pkgs.callPackage
+    ({ emacsPackages }:
+      emacsPackages.trivialBuild {
+        pname = "bag";
+        version = "1.0.0";
+        src = ./bag.el;
+        packageRequires =
+          (with depot.users.wpcarro.emacs.pkgs; [
+            al
+            list
+          ]);
+      })
+    { };
+
+  emacs = (pkgs.emacsPackagesFor pkgs.emacs28).emacsWithPackages (epkgs: [ bag ]);
+in
+bag.overrideAttrs (_old: {
+  doCheck = true;
+  checkPhase = ''
+    ${emacs}/bin/emacs -batch \
+      -l ert -l ${./tests.el} -f ert-run-tests-batch-and-exit
+  '';
+})