fix: [#624] Fallback doesn't work

[hwbrzzl]

📑 Description

Closes goravel/goravel#624

✅ Checks

• Added test cases for my code

Pull Request Overview

This PR fixes issue [#624] by addressing the fallback mechanism not working. The changes include:

• Introducing a new fallback field in the Route struct.
• Modifying the Fallback() method to set the fallback handler.
• Adding a registerFallback() function and invoking it in various server start methods.

Comments suppressed due to low confidence (1)

route.go:286

• The registerFallback() function is called in several methods, which may lead to multiple registrations of the fallback middleware if those methods are invoked more than once. Consider ensuring that the fallback middleware is registered only once to avoid duplicate executions.

func (r *Route) registerFallback() {