Currently, Postgres.app shows a warning and refuses to launch from a location other than /Applications

This is a frequent complaint from users, eg.:

• Support placing the app in ~/Applications #469
• Postgres.app will not launch when installed to /Users/xxxxxxx/Applications #562
• App does not allow to run from other directories than /Applications #601
• Starting Intel-only binaries crashes on Apple Silicon when Rosetta is not installed #638 (comment)
• latest version crashes on startup #593
• Postgress.app Can't Be Launched in /Applications sub-folders #678
• PostgresApp Only Executes ONLY from "/Applications" not sub-folder or other locations #684

As a first step towards making Postgres.app relocatable was to use relative links for shared libraries, which we completed a year ago:

• Postgres.app should not crash when launched from the wrong directory #639

Making Postgres.app relocatable causes a lot of potential issues, because then people could end up using multiple copies of Postgres.app simultaneously (on purpose or by accident). We've tried to document how we expect Postgres.app to behave on this Wiki page: https://github.com/PostgresApp/PostgresApp/wiki/Requirements-for-making-Postgres.app-relocatable

The next steps towards making Postgres.app relocatable are the following:

• Postgres.app should show binary path in server info #692
• User should be able to bypass /Applications check (implemented in 78d9ad8)
• Absolute paths in the GUI app should be replaced with relative paths (implemented in 561a2d8)
• LoginHelper and MenuHelper should work from locations other than /Applications