Add `set_symlink_permissions` and `access` functions to `DirExt` #1619

Job	Run time
Check Cross-Compilation on Rust nightly (nightly)	2m 56s
Check Cross-Compilation on Rust nightly on Windows (nightly)	2m 30s
Check Cross-Compilation on Windows (stable)	1m 24s
Check Cross-Compilation (stable)	1m 45s
Check Cross-Compilation on Windows (beta)	1m 19s
Check Cross-Compilation (beta)	2m 1s
Fuzz Targets	1m 10s
Rustfmt	7s
Test (stable)	34s
Test linux-raw support (ubuntu)	48s
Test (windows-latest)	1m 7s
Test on Musl (ubuntu)	1m 2s
Test linux-raw support (ubuntu-20.04)	53s
Test (msrv)	6m 1s
Test (windows-2019)	1m 5s
Test (macos-latest)	59s
Test (macos-11)	1m 5s
Test with Rust nightly (ubuntu)	52s
Test (beta)	52s
Test with Rust nightly (windows)	2m 38s
Test (ubuntu-20.04)	49s
Test (aarch64-ubuntu)	1m 20s
	33m 17s

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