Add PHPUnit icon

[ghost]

Closes #1091.
Follows the PHPUnit documentation. Requested in #997.

[shivapoudel]

Good @4086606 this closes #1091

[shivapoudel]

@4086606 Please also add phpunit-watcher configuration files .phpunit-watcher.yml, phpunit-watcher.yml and phpunit-watcher.yml.dist to map with PHPUnit icon.

Ref: https://github.com/spatie/phpunit-watcher#customization

@PKief In my opinion this PR is ready to go in the next update. PHPUnit icon looks pretty amazing in my VSCode and many thanks for introducing this SVG @4086606.

Closes #1091

[shivapoudel]

@4086606 Seems like the branch has a merge conflict still.

[PKief]

Nice icon, but please take a look at my comment!

[shivapoudel]

@PKief @4086606 Everything shaped up and looks nice to ship this in an upcoming version. Waiting for this and the composer icon badly :)

[fell-lucas]

Hello, is it possible to include .phpunit.result.cache on the list of files to use this icon? It's technically a JSON, but it has no icon for it at the moment.

[shivapoudel]

@4086606 Yeah this also can be included in the list!

[shivapoudel]

@PKief PHPUnit is probably ready. Can you please manage sometime to review this PR and get the merge done?

[PKief]

Thank you, looks great!

[shivapoudel]

@4086606 Can you also introduce a folder icon for PHPUnit?

Ref: https://github.com/wordpress/gutenberg