refactor: simplify logic of readFileAsString, remove redundant exists check

[b1tflyyyy]

Describe your PR, what does it fix/add?

Simplified logic of readFileAsString function, removed redundant exists check, changed function signature from std::string to std::filesystem::path

Is there anything you want to mention? (unchecked code, possible bugs, found problems, breaking compatibility, etc.)

No.

Did you use AI in any way shape or form in the making of this PR? If so, detail how you used it. (Undisclosed AI use is a violation of the AI Policy and is punishable)

No.

Is it ready for merging, or does it need work?

Ready for merging. Tested locally on my machine.

[vaxerski]

you should move all callers to Hyprutils::File::readFileAsString instead

[b1tflyyyy]

you should move all callers to Hyprutils::File::readFileAsString instead

So, I should use Hyprutils::File::readFileAsString function from here instead of NFsUtils::readFileAsString implementation?

And I need to replace all NFsUtils::readFileAsString calls with Hyprutils::File::readFileAsString?
In this case we can remove NFsUtils::readFileAsString implementation, am I right?