Use custom traits instead of libstd's `MetadataExt` and `PermissionsExt`. #1635

Job	Run time
Check Cross-Compilation on Rust nightly (nightly)	1m 16s
Check Cross-Compilation on Rust nightly on Windows (nightly)	47s
Check Cross-Compilation (stable)	59s
Check Cross-Compilation on Windows (stable)	47s
Rustfmt	11s
Check Cross-Compilation (beta)	1m 5s
Check Cross-Compilation on Windows (beta)	40s
Test (stable)	27s
Test (windows-latest)	57s
Test on Musl (ubuntu)	43s
Test linux-raw support (ubuntu)	37s
Test (windows-2019)	56s
Test with Rust nightly (ubuntu)	30s
Test linux-raw support (ubuntu-20.04)	30s
Test (macos-latest)	1m 7s
Test with Rust nightly (windows)	37s
Test (macos-11)	1m 5s
Test (beta)	31s
Fuzz Targets	48s
Test (msrv)	2m 8s
Test (ubuntu-20.04)	27s
Test (aarch64-ubuntu)	1m 15s
	18m 23s

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