Some entities are not rendered as bright as they should be when part of any spawner

Some entities are not rendered as bright as they should be when used as the 'displayEntity' (or rather, the 'summoned mob') of a spawner.

Steps to Reproduce:

1. Place down a monster spawner, or trial spawner
2. Use a blaze spawner on it
3. Tick freeze for easy observation

   /tick freeze

Observed & Expected Results:

- The blaze is rendered very dim compared to when the blaze is spawned as an entity.
- The blaze would be rendered exactly how it is rendered in entity form.

Screenshots/Videos:

Notes:

1. This also affects all entities that are burning:

   /give @p spawner{BlockEntityTag:{SpawnData:{entity:{id:"minecraft:zombie",Fire:1000,HasVisualFire:1b}}}} 1
   

2. Currently affected entities are:
   

Code Analysis:

The entities listed are affected because they override the `getBlockLightLevel()` method inside `net.minecraft.world.entity.Entity` by always returning 15 (the brightest block light level) instead of using a shader to render brighter like done with the emissive 'eye' layers of entities such as spiders, endermen, or phantoms (which all behave normally inside spawners).

The regular behavior for entities:

net.minecraft.world.entity.Entity

   protected int getBlockLightLevel(T entityType, BlockPos blockPos) {
      return entityType.isOnFire() ? 15 : entityType.level().getBrightness(LightLayer.BLOCK, blockPos);
   }

(As an example) The behavior for blazes:

net.minecraft.client.renderer.entity.BlazeRenderer

   protected int getBlockLightLevel(Blaze entityType, BlockPos blockPos) {
      return 15;
   }