feat(wpcarro/emacs): Package symbol.el

Not sure how useful this package is, *but* I'm packaging everything I have now,
and then in a separate CL I can refactor and remove various libs.

Change-Id: Id106539b19244ea1586198992c7ce0d65a0a242b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6014
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

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

@@ -0,0 +1,24 @@
+{ pkgs, depot, ... }:
+
+let
+  symbol = pkgs.callPackage
+    ({ emacsPackages }:
+      emacsPackages.trivialBuild {
+        pname = "symbol";
+        version = "1.0.0";
+        src = ./symbol.el;
+        packageRequires = [ ];
+      })
+    { };
+
+  emacs = (pkgs.emacsPackagesFor pkgs.emacs28).emacsWithPackages (epkgs: [
+    symbol
+  ]);
+in
+symbol.overrideAttrs (_old: {
+  doCheck = true;
+  checkPhase = ''
+    ${emacs}/bin/emacs -batch \
+      -l ert -l ${./tests.el} -f ert-run-tests-batch-and-exit
+  '';
+})