Add features related to how many horses the trainer has in the race

[hankehly]

• Multiple Entries Strategy: Indicators or features that capture the trainer's historical performance when entering multiple horses in a single race. This could include statistics on how often the trainer's horses tend to win or place in such scenarios.
• Trainer's Horses Interaction: Features that capture the interaction between multiple horses trained by the same person in the race, such as the difference in their performance metrics or strategies in races with multiple entries from the same trainer.
• Number of other horses by same trainer in the race