Improve the support for China's Standards of Encryption Algorithms

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• 为Sm3Hash实现digest::Digest等trait

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The bench shows that using the sm3 crate can have x150 improvement.

sha256_digest           time:   [256.18 ns 258.53 ns 261.12 ns]
                        change: [-3.4525% -1.9811% -0.5384%] (p = 0.00 < 0.05)
                        Change within noise threshold.
Found 8 outliers among 100 measurements (8.00%)
  6 (6.00%) high mild
  2 (2.00%) high severe

sm3_digest              time:   [4.0891 ns 4.1061 ns 4.1240 ns]
                        change: [-4.8771% -3.4558% -1.9811%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 9 outliers among 100 measurements (9.00%)
  5 (5.00%) high mild
  4 (4.00%) high severe

libsm_digest            time:   [601.86 ns 604.12 ns 606.56 ns]
                        change: [-5.8382% -4.5663% -3.1834%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
  1 (1.00%) low mild
  6 (6.00%) high mild
  3 (3.00%) high severe