slots_twig: Allow to check if a slot has content

Tested with D10.4.1 and php8.3, solution works as proposed.

Tested with D11.0.12 and it works as suggested, but only if I apply the patch locally as 37.diff using "plain diff".
The downloadable 37.patch fails.

Rly nice, thx for the idea adoption!

@all who are using this patch already, pls make sure to adjust your code. Harlor updated the issue summary with an up-to-date documentation.

Tested with Drupal 10.4.5 and slots dev-version

hey thx for testing! This has already been merged to 1.x

Automatically closed - issue fixed for 2 weeks with no activity.