gwen: Point macOS bundle metadata at Gwen icons

The icon rename removed app-icon-*.png but left the cargo-bundle
metadata referencing them, so bundle-mac could not produce an app
bundle. Point every channel at app-icon-gwen*.png, align bundle
identifiers and names with release_channel (com.yrkaierx.Gwen*), and
rename the DMG artifact and volume to Gwen.

script/bundle-mac

@@ -249,7 +249,7 @@ function sign_app_binaries() {
     else
         dmg_target_directory="target/${target_triple}/${target_dir}"
         dmg_source_directory="${dmg_target_directory}/dmg"
-        dmg_file_path="${dmg_target_directory}/Zed-${arch_suffix}.dmg"
+        dmg_file_path="${dmg_target_directory}/Gwen-${arch_suffix}.dmg"
         xcode_bin_dir_path="$(xcode-select -p)/usr/bin"
 
         rm -rf ${dmg_source_directory}
@@ -261,7 +261,7 @@ function sign_app_binaries() {
         ln -s /Applications ${dmg_source_directory}
 
         echo "Creating final DMG at ${dmg_file_path} using ${dmg_source_directory}"
-        hdiutil create -volname Zed -srcfolder "${dmg_source_directory}" -ov -format UDZO "${dmg_file_path}"
+        hdiutil create -volname Gwen -srcfolder "${dmg_source_directory}" -ov -format UDZO "${dmg_file_path}"
 
         # If someone runs this bundle script locally, a symlink will be placed in `dmg_source_directory`.
         # This symlink causes CPU issues with Zed if the Zed codebase is the project being worked on, so we simply remove it for now.