Feat: Create FastAPI

[pa-t]

Created a FastAPI to let users interface with open genmoji through API requests.

Current steps to get running

1. In the subdirectory genmoji/ copy the .env.sample and create a .env then add your huggingface token
2. Follow these steps to set up a conda env and run the api

cd gemoji/
conda create -n 'open_genmoji' python=3.11 -y
conda activate open_genmoji
pip install -r requirements.txt
uvicorn main:app --host 0.0.0.0 --port 8000 --workers 2

If there is interest in merging this in, the README should be updated with instructions