Create Gymnasium environment: multi-armed bandit

[jgvictores]

Create Gymnasium (gymnasium>=0.26.3) environment: multi-armed bandit.

Help:

• https://gymnasium.farama.org/tutorials/environment_creation
• https://github.com/axb2035/gym-examples (more updated than https://github.com/Farama-Foundation/gym-examples but beware https://github.com/axb2035/gym-examples/blob/88df1ddb653aef5312a967671dae49db4a18d21a/setup.py#L6 must be updated)
• https://github.com/jgvictores/awesome-deep-reinforcement-learning/commit/1be08c459cc2cd4040bba30d9012abb1ee40da71

[jgvictores]

Added via https://github.com/roboticslab-uc3m/gymnasium-playground/commit/66350c006feb7398cb838b271c0d843580050a47