🚀 [Feature]: Allow optional params with route constraints

[jamestiotio]

Description

This PR allows users to define routes with both optional parameters and constraints.

This PR fixes #2170.

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• For new functionalities I follow the inspiration of the express js framework and built them similar in usage
• I have performed a self-review of my own code
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I tried to make my code as fast as possible with as few allocations as possible
• For new code I have written benchmarks so that they can be analyzed and improved

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[ReneWerner87]

can you please put an example in the documentation so that everyone knows that the feature exists and how to use it?
https://docs.gofiber.io/guide/routing#constraints

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