Add circulating supply endpoint for OGV

[micahalcorn]

OGV version of this:

origin-website/views/web_views.py

Lines 320 to 324 in 0afb7b8

	@app.route("/circulating-ogn", strict_slashes=False)
	@app.route("/<lang_code>/circulating-ogn", strict_slashes=False)
	def circulating_ogn():
	data = token_stats.get_ogn_stats()
	return make_response(str(data["ogn_supply_stats"]["circulating_supply"]), 200)

Here is what the calculation should look like:
https://docs.google.com/spreadsheets/d/1ITSOrCrkFfn71eM6M-BmlpGV6t8hMV2csqp_pyVeji4/edit#gid=1182634713