jenv: install fish function symlinks

[davidxia]

The caveat isn't compatible with fish shell.
This PR changes the caveat for fish shell to show the
commands specified in the upstream's README here [1].

This PR does not change the caveat for other shells.

fixes jenv/jenv#315

I have tested this PR and get the output below.

With bash set as default shell (chsh -s $(which bash)):

brew info jenv

jenv: stable 0.5.4, HEAD
Manage your Java environment
https://www.jenv.be/
/opt/homebrew/Cellar/jenv/0.5.4 (82 files, 72.3KB) *
  Built from source on 2021-05-07 at 17:19:07
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/jenv.rb
License: MIT
==> Options
--HEAD
	Install HEAD version
==> Caveats
To activate jenv, add the following to your /Users/dxia/.bash_profile:

  export PATH="$HOME/.jenv/bin:$PATH"
  eval "$(jenv init -)"
==> Analytics
install: 9,672 (30 days), 30,663 (90 days), 129,619 (365 days)
install-on-request: 9,670 (30 days), 30,635 (90 days), 128,558 (365 days)
build-error: 0 (30 days)

With fish set as default shell:

brew info jenv

jenv: stable 0.5.4, HEAD
Manage your Java environment
https://www.jenv.be/
/opt/homebrew/Cellar/jenv/0.5.4 (82 files, 72.3KB) *
  Built from source on 2021-05-07 at 17:19:07
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/jenv.rb
License: MIT
==> Options
--HEAD
	Install HEAD version
==> Caveats
To activate jenv, run the following commands:

  echo 'set -g fish_user_paths "/opt/homebrew/opt/jenv/bin" $fish_user_paths' >> ~/.config/fish/config.fish
  echo 'status --is-interactive; and source (jenv init -|psub)' >> ~/.config/fish/config.fish
  cp /opt/homebrew/opt/jenv/libexec/fish/jenv.fish ~/.config/fish/functions/jenv.fish
  cp /opt/homebrew/opt/jenv/libexec/fish/export.fish ~/.config/fish/functions/export.fish
==> Analytics
install: 9,672 (30 days), 30,663 (90 days), 129,619 (365 days)
install-on-request: 9,670 (30 days), 30,635 (90 days), 128,558 (365 days)
build-error: 0 (30 days)

1: https://github.com/jenv/jenv/blob/9bbc5ebfe6f38252a1a0f28897c7ae52e6a483a0/README.md

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

---

[davidxia]

@carlocab Thanks for reviewing. Let me know any next steps required from me. If none, would be great to have this merged in.

[davidxia]

Bumping to see what else I can do to move this forward. It seems like this thread is the only unresolved one? #76864 (comment)

[cap10morgan]

I started to create a PR with more or less these same changes and then found this. This all works for me and is a big improvement over the current (broken) instructions. Thanks @davidxia!

[carlocab]

I don't mind merging this, subject to one suggestion, and pending the answer to one question.

[cap10morgan]

Hopefully have the last part in here as adoptable suggestions (in case that's helpful; feel free to ignore if not).

[carlocab]

Great, I think we can merge this soon. Let's just try to clean up the whitespace a bit; I don't think we need this much.

[cap10morgan]

FWIW the old title of this PR is still appropriate for it. Or at least both effects are pretty important here (i.e. fixing the fish caveat instructions and installing the functions in the appropriate place).

[carlocab]

Thanks, @davidxia, @cap10morgan.