UPDATE: split the webapp in a widget and the app itself

This splits the webapp in:

* IronCalc (the widget to be published on npmjs)
* The frontend for our "service"
* Adds "dummy code" for the backend using sqlite

webapp/app.ironcalc.com/server/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "ironcalc_server"
+version = "0.3.0"
+edition = "2021"
+
+[dependencies]
+rocket = "0.5"
+rand = "0.8"
+ironcalc = { path = "../../../xlsx/"}
+
+[dependencies.rocket_db_pools]
+version = "0.2.0"
+features = ["sqlx_sqlite"]
+