buildMozillaMach: support disabling extension signing enforcement

Previously, derivations specified the environment variable themselves,
which did not actually disable signing enforcement.

pkgs/applications/networking/browsers/firefox/common.nix

···
 , application ? "browser"
 , applicationName ? "Mozilla Firefox"
 , branding ? null
+, requireSigning ? true
 , src
 , unpackPhase ? null
 , extraPatches ? []
···
     configureFlagsArray+=("--with-mozilla-api-keyfile=$TMPDIR/mls-api-key")
   '' + lib.optionalString (enableOfficialBranding && !stdenv.is32bit) ''
     export MOZILLA_OFFICIAL=1
+  '' + lib.optionalString (!requireSigning) ''
+    export MOZ_REQUIRE_SIGNING=
   '' + lib.optionalString stdenv.hostPlatform.isMusl ''
     # linking firefox hits the vm.max_map_count kernel limit with the default musl allocator
     # TODO: Default vm.max_map_count has been increased, retest without this

pkgs/applications/networking/browsers/firefox/packages.nix

···
     };
   };
 
-  firefox-devedition = (buildMozillaMach rec {
+  firefox-devedition = buildMozillaMach rec {
     pname = "firefox-devedition";
     version = "116.0b3";
     applicationName = "Mozilla Firefox Developer Edition";
+    requireSigning = false;
     branding = "browser/branding/aurora";
     src = fetchurl {
       url = "mirror://mozilla/devedition/releases/${version}/source/firefox-${version}.source.tar.xz";
···
       versionSuffix = "b[0-9]*";
       baseUrl = "https://archive.mozilla.org/pub/devedition/releases/";
     };
-  }).overrideAttrs (prev: {
-    env.MOZ_REQUIRE_SIGNING = "";
-  });
+  };
 
   firefox-esr-102 = buildMozillaMach rec {
     pname = "firefox-esr-102";

pkgs/applications/networking/browsers/firefox/wrapper.nix

···
 
       nameArray = builtins.map(a: a.name) (lib.optionals usesNixExtensions nixExtensions);
 
-      requiresSigning = browser ? MOZ_REQUIRE_SIGNING
-                     -> toString browser.MOZ_REQUIRE_SIGNING != "";
-
       # Check that every extension has a unqiue .name attribute
       # and an extid attribute
       extensions = if nameArray != (lib.unique nameArray) then
         throw "Firefox addon name needs to be unique"
-      else if requiresSigning && !lib.hasSuffix "esr" browser.name then
-        throw "Nix addons are only supported without signature enforcement (eg. Firefox ESR)"
+      else if browser.requireSigning then
+        throw "Nix addons are only supported with signature enforcement disabled"
       else builtins.map (a:
         if ! (builtins.hasAttr "extid" a) then
         throw "nixExtensions has an invalid entry. Missing extid attribute. Please use fetchfirefoxaddon"

pkgs/applications/networking/browsers/librewolf/default.nix

···
 let
   librewolf-src = callPackage ./librewolf.nix { };
 in
-((buildMozillaMach rec {
+(buildMozillaMach rec {
   pname = "librewolf";
   applicationName = "LibreWolf";
   binaryName = "librewolf";
   version = librewolf-src.packageVersion;
   src = librewolf-src.firefox;
+  requireSigning = false;
   inherit (librewolf-src) extraConfigureFlags extraPatches extraPostPatch extraPassthru;
 
   meta = {
···
 }).override {
   crashreporterSupport = false;
   enableOfficialBranding = false;
-}).overrideAttrs (prev: {
-  MOZ_REQUIRE_SIGNING = "";
-})
+}