Centering the Network Graph

[frankcholula]

The network graph floats around on each page refresh.
Need to use config builder to lock the network graph in place.
Sample code here:

from streamlit_agraph.config import Config, ConfigBuilder

# 1. Build the config (with sidebar to play with options) .
config_builder = ConfigBuilder(nodes)
config = config_builder.build()

# 2. If your done, save the config to a file.
config.save("config.json")

# 3. Simple reload from json file (you can bump the builder at this point.)
config = Config(from_json="config.json")