migrate from flask to quart.

also remove all flaskiness from static file serving.
and reference all vendored scripts on the base tempĺate for simplicity.

lnbits/extensions/diagonalley/views.py

@@ -1,15 +1,11 @@
-import json
-
-from flask import g, abort, render_template, jsonify
+from quart import g, render_template
 
 from lnbits.decorators import check_user_exists, validate_uuids
 from lnbits.extensions.diagonalley import diagonalley_ext
-from lnbits.db import open_ext_db
 
 
 @diagonalley_ext.route("/")
 @validate_uuids(["usr"], required=True)
 @check_user_exists()
-def index():
-
-    return render_template("diagonalley/index.html", user=g.user)
+async def index():
+    return await render_template("diagonalley/index.html", user=g.user)