[11.x] Mark sdc as obsolete for 11.x

I think this will be easier to get rolling as a patch, rather than an MR.

As well as the lifecycle change, we'd also want a hook_update_N() to uninstall the module, and a hook_requirements() to prevent it being installed again. These ensure (as much as we can) that the module is actually uninstalled when we remove the code in Drupal 12.

Updated IS with suggestions from @catch.

🌱 [META] Move code from the experimental SDC module to core Active landed! 😄

This was completed as part of 📌 Remove SDC deprecated twig functions before 11.0.0 Postponed .