crypto: optimize getBytesOfRS for EC keys

[panva]

We only need the group order bit count here, which OpenSSL already caches on the key. Use that instead of reconstructing the group and decoding the public point.

[nodejs-github-bot]

Review requested:

• @nodejs/crypto
• @nodejs/security-wg

[github-actions]

Benchmark GHA (crypto / webcrypto-sign): https://github.com/nodejs/node/actions/runs/34160449761

Results

[!WARNING]
Do not take GHA benchmark results as face value, always confirm them
using a dedicated machine, e.g. Jenkins CI.

Benchmark results:

                                                                                              confidence improvement accuracy (*)    (**)   (***)
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='parallel' keyType='ec'                       ***     20.99 %      ±11.10% ±14.64% ±18.79%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='parallel' keyType='ed25519'                          -0.29 %       ±9.11% ±12.01% ±15.41%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='parallel' keyType='ml-dsa-44'                         1.08 %       ±9.32% ±12.29% ±15.77%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='parallel' keyType='rsa-pss'                           0.63 %       ±5.66%  ±7.47%  ±9.58%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='parallel' keyType='rsassa-pkcs1-v1_5'                 1.14 %       ±5.92%  ±7.80% ±10.01%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='serial' keyType='ec'                          **     18.23 %      ±11.20% ±14.77% ±18.95%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='serial' keyType='ed25519'                             1.14 %       ±9.47% ±12.49% ±16.02%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='serial' keyType='ml-dsa-44'                           0.89 %       ±8.78% ±11.58% ±14.86%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='serial' keyType='rsa-pss'                             0.59 %      ±10.16% ±13.39% ±17.18%
crypto/webcrypto-sign.js n=1000 keyReuse='shared' mode='serial' keyType='rsassa-pkcs1-v1_5'                   0.25 %      ±10.17% ±13.41% ±17.21%
crypto/webcrypto-sign.js n=1000 keyReuse='unique' mode='parallel' keyType='ec'                       ***     18.38 %      ±10.72% ±14.13% ±18.14%
crypto/webcrypto-sign.js n=1000 keyReuse='unique' mode='parallel' keyType='ed25519'                           2.71 %       ±9.02% ±11.89% ±15.25%
crypto/webcrypto-sign.js n=1000 keyReuse='unique' mode='parallel' keyType='ml-dsa-44'                        -1.05 %       ±9.11% ±12.00% ±15.40%
crypto/webcrypto-sign.js n=1000 keyReuse='unique' mode='parallel' keyType='rsa-pss'                           0.91 %       ±5.39%  ±7.11%  ±9.12%
crypto/webcrypto-sign.js n=1000 keyReuse='unique' mode='parallel' keyType='rsassa-pkcs1-v1_5'                 1.37 %       ±4.92%  ±6.48%  ±8.32%

Be aware that when doing many comparisons the risk of a false-positive
result increases. In this case, there are 15 comparisons, you can thus
expect the following amount of false-positive results:
  0.75 false positives, when considering a   5% risk acceptance (*, **, ***),
  0.15 false positives, when considering a   1% risk acceptance (**, ***),
  0.01 false positives, when considering a 0.1% risk acceptance (***)

[!WARNING]
Do not take GHA benchmark results as face value, always confirm them
using a dedicated machine, e.g. Jenkins CI.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/77175/