Add LambdaCallback

[marload]

🚀 Feature

Add LambdaCallback for quick and easy callback creation.

Motivation

Previously, we had to make a callback class in order to make a callback. However, Lambda Callback makes it easy to create a simple Callback without declaring a Class. TensorFlow officially provides this callback, which can be used very efficiently.

https://www.tensorflow.org/api_docs/python/tf/keras/callbacks/LambdaCallback

Pitch

Add a new callback, LambdaCallback

Alternatives

Additional context

[github-actions]

Hi! thanks for your contribution!, great first issue!

[marload]

If this feature is considered useful, I'm going to contribute.

[tchaton]

Hey @marload,

Yes, it would definitely be a great addition. Let's follow Keras API as it is pretty intuitive !
Feel free to submit a PR and ping me as reviewer.

Best,
T.C