* implement Op<Statx> and use it to implement fs::try_exists
* fix statx on unavailable platforms
* complete using only io-uring operations for read_uring
* Implemented io-uring::Op<Statx> and apply it accordingly to read_uring, try_exists
* Added test for io uring statx operations. Checks for cancellations, shutdown, stating multiple files, ELOOP, ENAMETOOLONG, EACCES
* Removed musl as supported platform for io_uring statx operations, as statx is supported on 1.25+ musl, and MSRV that uses 1.25 on all *-linux-musl platforms is 1.93
* Removed pending checks for cancel_op_future since io_uring not available on Linux <5.1, removed stat permission denied test case since it doesn't work on Linux 4.19
* Removed redundant cfg attributes on functions, added STATX_BTIME flag in statx operation, use assert pending in cancel ops
* Uncommented stat_permission_denied test and make sure it doesn't run on platforms that don't support io_uring, removed unnecessary comments, and added TODO on symlink_metadata for when Metadata::from_statx is stabilized
* Statx fd leak drop test added and added STATX_BTIME to file_metadata
* Remove unnecessary utils function, refactored code in statx and statx fd leak test, and removed cfg_io_uring gates (localized the feature gate to the pertinent part of the code that uses it in read_uring)
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Co-authored-by: Vrtgs <[email protected]>
