Chore - Add BukkitApollo#toApolloEntity utility method

[ItsNature]

Overview

Description:
Added utility method for Bukkit Entity to ApolloEntity conversion.

Changes:
Added BukkitApollo#toApolloEntity(org.bukkit.entity.Entity) method

Code Example (If applicable):

public void runEntityExample(Player player, ApolloPlayer apolloPlayer) {
      List<ApolloEntity> sheepEntities = player.getWorld().getEntitiesByClass(Sheep.class)
          .stream().map(BukkitApollo::toApolloEntity)
          .collect(Collectors.toList());

      this.entityModule.overrideRainbowSheep(apolloPlayer, sheepEntities);
  }

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Review Request Checklist

• Your code follows the style guidelines of this project.
• I have performed a self-review of my code.
• I have tested this change myself. (If applicable)
• I have made corresponding changes to the documentation. (If applicable)
• The branch name follows the projects naming conventions. (e.g. feature/add-module & bugfix/fix-issue)

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