Safer dynamic event handling for observers #46981

Job	Run time
build (windows-latest)	4m 54s
toml	2m 11s
build (ubuntu-latest)	2m 34s
build (macos-latest)	1m 50s
check-bevy-internal-imports	4s
check-doc	7m 46s
check-missing-examples-in-docs	29s
ci	2m 24s
run-examples-macos-metal	6m 44s
miri	8m 22s
typos	9s
check-missing-features-in-docs	28s
markdownlint	1m 11s
check-compiles	4m 40s
build-wasm	51s
build-wasm-atomics	1m 43s
msrv	59s
	47m 19s

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