Add /Applications shortcut to macOS dmg file

[messense]

Fixes #5205

Changes proposed in this pull request:

• Use dmgbuild to create macOS dmg file with a shortcut to /Applications and a simple arrow background (can be changed to something else if you design a better background image).

[wetneb]

Thanks a lot for tackling this @messense!

I tried building the DMG with your new pipeline on Linux and was not sure if it would be supported. It did generate a DMG file, but the internal structure seems to be wrong (when opening the DMG in MacOS VM):

Since I am not getting the same result as you, I suspect this is just a consequence of the fact that I built on Linux?
In the CI, we are building with MacOS, so I would be tempted to just merge this and see if the DMG built by the CI works as expected.

[messense]

I suspect this is just a consequence of the fact that I built on Linux?

I've only tested on arm64 macOS, looking at the CI configuration of dmgbuild they also only test on macOS: https://github.com/dmgbuild/dmgbuild/blob/main/.github/workflows/ci.yml

[messense]

https://github.com/dmgbuild/mac_alias

While it is written in pure Python, some OS X specific code is required to generate a proper Alias or Bookmark record for a given file, so this module currently is not portable to other platforms.

I think because dmgbuild depends on mac_alias, it's also not portable to non-macOS platforms..

[wetneb]

Alright then let's just merge this and I'll check the output from the CI. Exciting!

[wetneb]

It works as expected. Thanks again! I have awarded the corresponding bounty to you on IssueHunt.