Use EventrwflagsDetails in fmt::Debug impl for wasi::Event #471

Job	Run time
TestWakerPipe	28s
Test (ubuntu-latest)	41s
Test (macos-latest)	41s
CheckTargets	1m 26s
Check (aarch64-apple-ios)	32s
Clippy	16s
Test (windows-latest)	2m 34s
Check (aarch64-apple-tvos)	35s
Docs	7s
Check (aarch64-unknown-openbsd)	31s
MinimalVersions (ubuntu-latest)	18s
Check (arm64_32-apple-watchos)	30s
MSRV (ubuntu-latest)	10s
MinimalVersions (macos-latest)	25s
Nightly	20s
Check (armv7-sony-vita-newlibeabihf)	34s
MSRV (macos-latest)	16s
MinimalVersions (windows-latest)	57s
MSRV (windows-latest)	35s
Check (sparcv9-sun-solaris)	27s
Check (x86_64-pc-solaris)	28s
Rustfmt	8s
Sanitizer (address)	42s
Check (x86_64-unknown-dragonfly)	32s
TestPoll	27s
Sanitizer (leak)	37s
Check (x86_64-unknown-openbsd)	29s
Sanitizer (memory)	1m 8s
Sanitizer (thread)	40s
Passed	1s
	17m 35s

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