Use HTML swap to display success and error messages

src/templates.rs

@@ -0,0 +1,13 @@
+use askama::Template;
+
+#[derive(Template)]
+#[template(path = "../templates/success.html")]
+pub struct SuccessTemplate {
+    pub success_message: String,
+}
+
+#[derive(Template)]
+#[template(path = "../templates/error.html")]
+pub struct ErrorTemplate {
+    pub error_message: String,
+}