postman: 7.0.7 -> 7.6.0

- Remove gnome2 (#39976)
  - Use pango instead of gnome2.pango
  - Remove gnome2.GConf
  - Remove gtk2-x11
- Add at-spi2-atk dependency
- Explicitly import packages rather than just pkgs or xorg
- Refactor patchelf to be more generic
- Use wrapGAppsHook
  - As this app uses GTK3 for the UI, we need to use wrapGAppsHook
- Move libPath creation to postFixup
- Remove dontPatchELF
- Remove unnecessary Postman binary, only use _Postman
- Remove unnecessary makeWrapper
- Add dontConfigure
- Remove unnecessary lib 
- Move libPath inputs to buildInputs