feat: Add new Rhai example demonstrating payment flow

- Add a new Rhai example showcasing complete payment flow
  for company registration. This includes company creation,
  payment record creation, successful payment processing,
  status updates, and handling failed and refunded payments.
- Add new example demonstrating payment integration in Rhai
  scripting.  This example showcases the usage of various
  payment status methods and verifies data from the database
  after processing payments.
- Add new examples to Cargo.toml to facilitate building and
  running the examples.  This makes it easier to integrate
  and test payment functionality using Rhai scripting.

heromodels/Cargo.toml

@@ -83,3 +83,8 @@ required-features = ["rhai"]
 name = "biz_rhai"
 path = "examples/biz_rhai/example.rs"
 required-features = ["rhai"]
+
+[[example]]
+name = "payment_flow_rhai"
+path = "examples/biz_rhai/payment_flow_example.rs"
+required-features = ["rhai"]