Treewide: add meta.mainProgram for bupstash, fd, autossh and ssh-to-age

pkgs/tools/backup/bupstash/default.nix

@@ -29,5 +29,6 @@ rustPlatform.buildRustPackage rec {
     license = licenses.mit;
     platforms = platforms.unix;
     maintainers = with maintainers; [ andrewchambers ];
+    mainProgram = "bupstash";
   };
 }

pkgs/tools/misc/fd/default.nix

@@ -45,5 +45,6 @@ rustPlatform.buildRustPackage rec {
     changelog = "https://github.com/sharkdp/fd/blob/v${version}/CHANGELOG.md";
     license = with licenses; [ asl20 /* or */ mit ];
     maintainers = with maintainers; [ dywedir figsoda globin ma27 zowoq ];
+    mainProgram = "fd";
   };
 }

pkgs/tools/networking/autossh/default.nix

@@ -1,4 +1,4 @@
-{lib, stdenv, fetchurl, openssh}:
+{ lib, stdenv, fetchurl, openssh }:
 
 stdenv.mkDerivation rec {
   pname = "autossh";
@@ -31,5 +31,6 @@ stdenv.mkDerivation rec {
     license = licenses.bsd1;
     platforms = platforms.unix;
     maintainers = with maintainers; [ pSub ];
+    mainProgram = "autossh";
   };
 }

pkgs/tools/security/ssh-to-age/default.nix

@@ -26,5 +26,6 @@ buildGoModule rec {
     homepage = "https://github.com/Mic92/ssh-to-age";
     license = licenses.mit;
     maintainers = with maintainers; [ mic92 ];
+    mainProgram = "ssh-to-age";
   };
 }