Implement the http variant of the bank server.

During that process, many shortcomings with the socket server and the
bank lib were fixed.

I am aware a massive commit like this is not ideal.

http-server/src/handlers/create_account.rs

@@ -0,0 +1,29 @@
+use actix_web::{post, web, Responder, Result};
+use serde::{Deserialize, Serialize};
+
+use crate::AppState;
+
+#[derive(Serialize, Deserialize)]
+pub struct OwnerData {
+    pub(crate) owner: String,
+}
+
+#[derive(Serialize)]
+struct AccountCreated {
+    nr: String,
+}
+
+#[post("")]
+pub async fn route(
+    form: web::Form<OwnerData>,
+    data: web::Data<AppState>,
+) -> Result<impl Responder> {
+    let owner = &form.owner;
+    info!("creating new account with owner {}...", owner);
+
+    let mut bank = data.bank.write().unwrap();
+    let nr = bank.create_account(owner.clone());
+    info!("created account {}", nr);
+
+    Ok(web::Json(AccountCreated { nr }))
+}