Improve Fish path setup on macOS

[drewcassidy]

Feature or enhancement

Improve the path setup on macOS for users of the Fish shell

Pitch

Right now, the installer sets up python paths the same way as on every other shell: by appending a line to the end of the config file that adds directly to $PATH. Modifying the users config directly is not the best way to do this in fish, which has a conf.d directory to place configs into instead. In addition, fish has the fish_add_path function that doesn't allow duplicate entries in the PATH which can get out of hand when re-sourcing the config file multiple times.

I am working on a PR to address this right now, by writing a file for each python install to conf.d which adds the path using fish_add_path

Linked PRs

• gh-91629 Use conf.d configs and fish_add_path to set the PATH when installing for the Fish shell. #91630

[ned-deily]

Thanks for the PR and your patience. Merged for 3.13.