Better locate the bin directory

[duncancm9]

The bin directory can be changed: https://getcomposer.org/doc/articles/vendor-binaries.md#can-vendor-binaries-be-installed-somewhere-other-than-vendor-bin-

So that can break:

https://github.com/fourkitchens/fire/blob/2.x/src/Robo/Plugin/Commands/FireCommandBase.php#L95-L101

But it seems that as of 2.2.2 they help to tell us where it is:
https://getcomposer.org/doc/articles/vendor-binaries.md#finding-the-composer-bin-dir-from-a-binary

[duncancm9]

Or perhaps we change to:

  /**
   * Returns fire's vendors executable.
   *
   * @return string
   */
  public function getFireExecutable() {
    return $this->vendorPath . 'fourkitchens/fire/bin/fire';
  }

However it loses this bit if wrapped in the bin file:

/**
 * Proxy PHP file generated by Composer
 *
 * This file includes the referenced bin path (../vendor/fourkitchens/fire/bin/fire)
 * using a stream wrapper to prevent the shebang from being output on PHP<8
 *
 * @generated
 */