♻️ Refactor: Use EnableColors instead of DisableColors

[ghost]

Description

In this pull request, initially, EnableColors was exported and used, but then a new a bool variable was added, which I feel like is redundant, since EnableColors already exists, and works just like the added DisableColors bool

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:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation - /docs/ directory for https://docs.gofiber.io/
• New and existing unit tests pass locally with my changes

Commit formatting:

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[ReneWerner87]

By default all variables with datatype bool are false, so how do you manage the default value true when a consumer passes a custom config and does not explicitly enable coloring

Therefore we mostly use switches that are rotated when the default value is "enabled".

[ghost]

Ah, I see, thank you for the clarification! @ReneWerner87
I'll close the PR.