[MU4] MacOS dmg name and image

[cbjeukendrup]

• Ported [MU3] Fix macOS dmg name, fix macOS dmg window height, update version number #7360: Fix macOS dmg name
• Partly ported [MU3] Update Installer imagery for Mac and Windows #7219: Update dmg imagery for macOS
  (Maybe not definitive, but at least nice for now, I would think.)

• I signed CLA
• I made sure the code in the PR follows the coding rules
• I made sure the code compiles on my machine
• I made sure there are no unnecessary changes in the code
• I made sure the title of the PR reflects the core meaning of the issue you are solving
• I made sure the commit message(s) contain a description and answer the question "Why do those changes fix that particular issue?" or "Why are those changes really necessary as improvements?"
• I made sure the commit message title starts with "fix #424242:" if there is a related issue
• I created the test (mtest, vtest, script test) to verify the changes I made