Rough implementation of task poll callbacks #11202

Job	Run time
fmt	20s
minrust	29s
Check README	3s
clippy	26s
docs (windows-latest)	29s
docs (ubuntu-latest, --cfg tokio_taskdump, --cfg tokio_taskdump)	29s
basic checks	0s
test tokio full	0s
test all crates in the workspace with all features and panic=abort	0s
test all crates in the workspace with all features	0s
check tokio full --internal-mt-counters	0s
Run integration tests for each feature	0s
test tokio full --unstable	0s
compile tests with parking lot send guards	0s
test tokio full --unstable --taskdump	0s
asan	0s
cross-check	0s
valgrind	0s
cross-check-tier3	0s
miri-doc	0s
miri-lib	0s
miri-test	0s
semver	0s
cross-test-with-parking_lot	0s
Test tokio --all-features on i686-unknown-linux-gnu without AtomicU64	0s
cross-test-without-parking_lot	0s
features ${{ matrix.name }}	0s
build loom tests	0s
minimal-versions	0s
Check tokio --feature-powerset --depth 2 on i686-unknown-linux-gnu without AtomicU64	0s
Test hyper	0s
Test Quinn	0s
check-external-types (${{ matrix.os }})	0s
build tokio for redox-os	0s
test tokio for wasm32-unknown-unknown	0s
${{ matrix.target }}	0s
build tokio for x86_64-fortanix-unknown-sgx	0s
check-fuzzing	0s
check-spelling	0s
check unexpected lints and cfgs	0s
all systems go	0s
	2m 16s

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