feat(rpc): add `blockTimestamp` to Log #1537

Job	Run time
docs	47s
clippy	1m 9s
cfg-check	27s
doctest	2m 18s
feature-checks	5m 24s
fmt	11s
no-std	32s
test stable --no-default-features	2m 13s
wasm-unknown	1m 38s
test stable	2m 14s
wasm-wasi	2m 32s
test stable --all-features	2m 33s
test nightly --no-default-features	1m 17s
test nightly	1m 13s
test nightly --all-features	1m 54s
test 1.76 --no-default-features	1m 25s
test 1.76	1m 22s
	29m 9s

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