Dimension Leak Fix

v1.0.3:
- First release for Forge and NeoForge. Same code and fixes as Dimension Leak Fix 1.0.3 for Fabric.
- When you change dimension or return to the menu, the world you left is emptied 3 seconds later, so a mod that still holds it only holds an empty shell. Leaving a singleplayer world also cleans up the stopped integrated server.
- Known leaks from other mods are released (Serene Seasons, Jade, Flywheel), touching only the references to the world or server you left.
- The log says when a world or server you left is really freed from memory, or that it is still there 5 minutes later.
- Install it on the client. A server does not need it; if a modpack ships it on the server anyway, it loads there and does nothing.
- On Minecraft 1.20.1 the same file runs on Forge and on NeoForge.
- No config file.