[Feature Request]: Streamline Payment initialize to dispatch `ProcessPayment`

### Preflight Checklist

- [x] I have read the [Contributing Guidelines](https://github.com/EnAccess/micropowermanager/blob/main/CONTRIBUTING.md) for this project, if it exists.
- [x] I agree to follow the [Code of Conduct](https://github.com/EnAccess/micropowermanager/blob/main/CODE_OF_CONDUCT.md) that this project adheres to.
- [x] I have searched the [issue tracker](https://github.com/EnAccess/micropowermanager/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

https://github.com/EnAccess/micropowermanager/pull/1385#discussion_r3091664608 proposes an improvement towards Payment initialization where each payment provider decides when to dispatch `ProcessPayment`.

With this we can further improve the payment flow logic.

### Proposed Solution

Move `ProcessPayment` dispatch into initialization of payment providers. Every provider should handle how and when it dispatches the process payment event.

### Alternatives Considered

N/A

### Additional Information

_No response_