[Console] Add descriptions to Fish completion output

[adriaanzon]

Q	A
Branch?	7.1
Bug fix?	no
New feature?	no
Deprecations?	no
Issues	N/A
License	MIT

This improves the completion output for the Fish shell to include descriptions. The -a option of Fish's complete command accepts a list where each line is an argument with an optional description, separated by a tab. The fish script doesn't need to change, making this change backwards compatible.

Since the output is now identical to that of ZshCompletionOutput, code duplication could still be reduced by extracting to an abstract class (e.g. TabSeparatedCompletionOutput) that gets extended by FishCompletionOutput and ZshCompletionOutput.

[carsonbot]

Hey!

I see that this is your first PR. That is great! Welcome!

Symfony has a contribution guide which I suggest you to read.

In short:

• Always add tests
• Keep backward compatibility (see https://symfony.com/bc).
• Bug fixes must be submitted against the lowest maintained branch where they apply (see https://symfony.com/releases)
• Features and deprecations must be submitted against the 7.1 branch.

Review the GitHub status checks of your pull request and try to solve the reported issues. If some tests are failing, try to see if they are failing because of this change.

When two Symfony core team members approve this change, it will be merged and you will become an official Symfony contributor!
If this PR is merged in a lower version branch, it will be merged up to all maintained branches within a few days.

I am going to sit back now and wait for the reviews.

Cheers!

Carsonbot

[GromNaN]

Works very well. Thank you Adriaan for this first great contribution.

Since the output is now identical to that of ZshCompletionOutput, code duplication could still be reduced by extracting to an abstract class (e.g. TabSeparatedCompletionOutput) that gets extended by FishCompletionOutput and ZshCompletionOutput.

It's identical code, but not "duplicated". It's better to keep 2 simple classes that serve a distinct purpose than to add complexity through inheritance.

[fabpot]

Thank you @adriaanzon.