JAX implementation of scipy.stats.multinomial

[harryjulian]

Please:

• [X] Check for duplicate requests.
• [X] Describe your goal, and if possible provide a code snippet with a motivating example.

Hi all,

Whilst working on a recent project I realised that scipy.stats.multinomial doesn't have a jax.scipy implementation.

I thought it'd be worthwhile to implement as well as a decent first contribution.

I think I'm largely done on the work here but thought to make an issue before making a PR.

Is there any reason this hasn't been implemented thus far?

[jakevdp]

I don't know of any reason it hasn't been implemented - feel free to open a PR if you'd like to contribute!