🩹 Fix: handle multiple X-Forwarded header

[supakornbabe]

Description

Fix the problem when the server is behind more than 2 proxies and c.BaseURL(), c.Protocol(), c.Hostname() will return the list instead of the first variable.

func LoginHandler(c *fiber.Ctx) error {
	fmt.Println("BaseURL: "+c.BaseURL())
	fmt.Println("Protocol: "+c.Protocol())
        fmt.Println("Hostname: "+c.Hostname())
}

Result

BaseURL: https, https://hello.world.com, hello.world.com
Protocol: https, https
Hostname: hello.world.com, hello.world.com

So this PR will fix these functions to return only first variable from list

Result

BaseURL: https://hello.world.com
Protocol: https
Hostname: hello.world.com

Fixes #2151

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

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 commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation - https://github.com/gofiber/docs for https://docs.gofiber.io/
• 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
• If new dependencies exist, I have checked that they are really necessary and agreed with the maintainers/community (we want to have as few dependencies as possible)
• 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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