Implement status operator for reading working tree status

[ramsey]

I'm working on a new feature for CaptainHook that requires inspecting the working tree through git status.

This PR provides git status output inspection, creating an array of Path objects, which can be checked for the current status of that path in the working tree (as compared to the index).

Example

Get the status and filter by paths added to the index.

use SebastianFeldmann\Git;

$repo = new Git\Repository(__DIR__);
$status = $repo->getStatusOperator();

$pathsAddedToIndex = array_filter(
    $status->getWorkingTreeStatus(),
    fn ($path) => $path->isAddedToIndex()
);

foreach ($pathsAddedToIndex as $path) {
    echo $path->getPath() . PHP_EOL;
}

[ramsey]

Build is failing when attempting to download the PHPStan Phar from the GitHub API.

[sebastianfeldmann]

Love it!

Looks really good. Merge incoming :)