✨ Add custom data property to favicon middleware config

[PassTheMayo]

Description

This pull request adds the Data property to the configuration of the favicon middleware, allowing the user to supply raw favicon data to the middleware instead of providing a file path. This allows the user to use //go:embed flags to load favicon data during build-time, and supply it to the middleware instead of reading the file every time the application starts.

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

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[gaby]

Run gofumpt -w . on the middlewars files

[gaby]

Besides formatting, lgtm

[welcome]

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