Add and use FeatureHooks.getAllEntities

The ServerLevel#getAllEntities function only returns entities which
are accessible. FeatureHooks#getAllEntities will return all
entities, whether or not they are accessible.

Use the new hook in the EntityCommand, which allows server admins
to inspect entities in unloaded chunks.

Use the hook as well for ticking the EntityScheduler. This fixes
an issue whether unloaded entities did not have their scheduler ticked.

paper-server/patches/sources/io/papermc/paper/FeatureHooks.java.patch

@@ -1,6 +1,6 @@
 --- /dev/null
 +++ b/io/papermc/paper/FeatureHooks.java
-@@ -1,0 +_,241 @@
+@@ -1,0 +_,246 @@
 +package io.papermc.paper;
 +
 +import io.papermc.paper.command.PaperSubcommand;
@@ -33,6 +33,11 @@
 +
 +public final class FeatureHooks {
 +
++    // this includes non-accessible entities
++    public static Iterable<Entity> getAllEntities(final net.minecraft.server.level.ServerLevel world) {
++        return ((net.minecraft.world.level.entity.LevelEntityGetterAdapter<Entity>)world.getEntities()).sectionStorage.getAllEntities();
++    }
++
 +    public static void setPlayerChunkUnloadDelay(final long ticks) {
 +    }
 +