Refactor: `ReplicationCore` get a snapshot directly from state machine, via `SnapshotReader` #3376

Job	Run time
stores (stores/memstore)	54s
openraft-test (stable, 0)	39s
stores (stores/rocksstore)	6m 16s
openraft-test (nightly, 30)	43s
stores (stores/sledstore)	1m 1s
openraft-test (nightly, 0, single-term-leader)	46s
cluster-benchmark (cluster_benchmark)	50s
examples (stable, memstore)	41s
lint	6m 36s
examples (stable, raft-kv-memstore)	2m 16s
examples (stable, raft-kv-memstore-generic-snapshot-data)	1m 3s
openraft-feature-test (nightly)	47s
examples (stable, raft-kv-memstore-opendal-snapshot-data)	1m 34s
openraft-feature-test (nightly, serde)	45s
openraft-test-bench (nightly)	47s
examples (stable, raft-kv-memstore-singlethreaded)	1m 4s
openraft-feature-test (nightly, single-term-leader)	43s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	47s
examples (stable, raft-kv-rocksdb)	8m 8s
examples (nightly, memstore)	52s
Build (nightly, bench,serde,bt,singlethreaded)	49s
examples (nightly, raft-kv-memstore)	2m 7s
tests-feature-test (nightly)	3m 10s
examples (nightly, raft-kv-memstore-generic-snapshot-data)	1m 20s
tests-feature-test (nightly, single-term-leader)	3m 12s
examples (nightly, raft-kv-memstore-opendal-snapshot-data)	1m 56s
tests-feature-test (nightly, loosen-follower-log-revert)	3m 15s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 25s
examples (nightly, raft-kv-rocksdb)	7m 5s
	1h 1m 31s

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