✨ feat: add Reset method to Session struct in session middleware

[kaptinlin]

Description

This pull request introduces a new Reset method to the Session struct in the Fiber's session middleware. The Reset method is designed to generate a new session id, delete the old one from storage, and reset the associated data. This functionality extends the existing session management methods such as getting, setting, and deleting session data, as well as destroying the session.

The motivation behind this change is to provide more flexibility in session management, especially in scenarios like repeated user logins. With the Reset method, we can easily invalidate the current session data and simultaneously create a new session, without the need to explicitly destroy and recreate the session as before. This simplifies the process and makes the code cleaner and more efficient.

This pull request also includes relevant test code to ensure the correct functionality of the Reset method. Additionally, some existing test code has been optimized to the session middleware.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

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 - /docs/ directory 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

Usage

// Initialize default config
// This stores all of your app's sessions
store := session.New()

app.Post("/login", func(c *fiber.Ctx) error {
    // Get session from storage
    sess, err := store.Get(c)
    if err != nil {
        panic(err)
    }

    // ... validate login ...

    // Check if the session is fresh
    if !sess.Fresh() {
        // If the session is not fresh, reset it
        if err := sess.Reset(); err != nil {
            panic(err)
        }
    }

    // Set new session data
    sess.Set("user_id", user.ID)

    // Save session
    if err := sess.Save(); err != nil {
        panic(err)
    }

    return c.SendString(fmt.Sprintf("Welcome %v", user.ID))
})

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[gaby]

Lets wait for the other PR to be merged. Then this one can be rebased.

[gaby]

Pending #2655