src,lib: expose getCategoryEnabledBuffer to use on node.http

[H4ad]

This PR is a simplified version of https://github.com/nodejs/node/pull/48142

With this function, I also plan to replace all the references of isTraceCategoryEnabled.

I made this function generic also to support cases like:

https://github.com/nodejs/node/blob/53ac448022b7cdfcc09296da88d9a1b59921f6bf/lib/internal/util/debuglog.js#L375

In this code, the category can be anything, so this function will handle those cases as well.