Add a helper script to ease path configuration

[tbussmann]

Currently, we recommend to use a medium complex command¹ to configure the path for CLI apps. This may scare users not used to the command line and doesn't give proper feedback it it was successful. Further, the Terminal window needs to be closed and reopened for the change to be effective. This instructions are given at docs/index.md, docs/documentation/install.md and docs/documentation/cli-tools.md but the restart is only mentioned at the last location.

In #735 (comment) the idea was expressed to include a shell script that takes care of setting the path which would be friendlier to call. This script could give a more verbose output, ask for password if ran w/o sudo and activate the new $PATH directly for the current session. Further, this script could take care of using the actual path in case Postgres.app is not in /Applications.

Maybe this script could even be called using a button in the preferences or from the menu, like tolls like BBEdit install their cmd-tooling.

Footnotes

1. sudo mkdir -p /etc/paths.d &&
   echo /Applications/Postgres.app/Contents/Versions/latest/bin | sudo tee /etc/paths.d/postgresapp ↩