feat: dpp::utility::if_success, a shortcut for callbacks

[Mishura4]

Convenience function to generate a function suitable for use as a callback to API calls. On success calls the given function, on error log the error to the cluster.

Example:

bot.message_create(message, dpp::utility::if_success([&bot](const dpp::message &m) {
	bot.log(dpp::ll_info, "message sent successfully");
}));

Code change checklist

• I have ensured that all methods and functions are fully documented using doxygen style comments.
• My code follows the coding style guide.
• I tested that my change works before raising the PR.
• I have ensured that I did not break any existing API calls.
• I have not built my pull request using AI, a static analysis tool or similar without any human oversight.

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[github-actions]

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