Feature: Add random number generator to `AsyncRuntime` #308

Job	Run time
cluster-benchmark (cluster_benchmark)	48s
external-stores (stores/rocksstore-v2)	6m 42s
examples (stable, raft-kv-memstore)	2m 11s
examples (stable, raft-kv-memstore-singlethreaded)	56s
lint	6m 36s
openraft-feature-test (nightly)	47s
openraft-test (stable, 0)	2m 51s
examples (stable, raft-kv-rocksdb)	8m 2s
openraft-feature-test (nightly, serde)	48s
openraft-test (nightly, 30)	3m 13s
examples (nightly, raft-kv-memstore)	2m 4s
openraft-feature-test (nightly, single-term-leader)	49s
openraft-test-bench (nightly)	53s
openraft-test (nightly, 0, single-term-leader)	3m 6s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 20s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	51s
examples (nightly, raft-kv-rocksdb)	12m 25s
Build (nightly, bench,serde,bt,singlethreaded)	48s
tests-feature-test (nightly)	2m 45s
stores (memstore)	41s
tests-feature-test (nightly, single-term-leader)	2m 46s
stores (rocksstore)	5m 54s
tests-feature-test (nightly, loosen-follower-log-revert)	2m 52s
stores (rocksstore-compat07)	6m 6s
stores (sledstore)	52s
	1h 17m 6s

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