xlog: introduce xlog_remove_file function for removing xlog files

Here are the two commits, first is cherry-pick from the tarantool upstream and the second one is for providing the ffi symbol for external usage from the rust code of picodata.

Summary

• feat: export xlog_remove_file_impl
• xlog: introduce xlog_remove_file function for removing xlog files

This commit introduces the xlog_remove_file() function that removes a file by name and logs the error on failure. We use this function everywhere we delete xlog files so that there's a single place where we call unlink(). We also factor out the core functionality to a callback function that can be overridden. This will help us implement thorough file deletion.

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• Part of https://git.picodata.io/picodata/picodata/docs/-/work_items/152?iid_path=true
• See also picodata/picodata/picodata!829