crypto: cache valid ECDH key pairs

[panva]

Avoid repeating EC key-pair validation after a pair has already been established or validated. Invalidate the positive-only cache whenever public-key mutation can make the pair inconsistent.

[nodejs-github-bot]

Review requested:

• @nodejs/crypto
• @nodejs/performance

[github-actions]

Benchmark GHA (crypto / ecdh-compute-secret): https://github.com/nodejs/node/actions/runs/33163372222

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/ecdh-compute-secret.js n=5000 scenario='first-after-generate'          ***     33.41 %       ±5.73% ±7.55% ±9.69%
crypto/ecdh-compute-secret.js n=5000 scenario='full-lifecycle'                ***     21.08 %       ±5.41% ±7.13% ±9.15%
crypto/ecdh-compute-secret.js n=5000 scenario='reused-local-peer-pool'        ***     32.58 %       ±5.65% ±7.45% ±9.57%
crypto/ecdh-compute-secret.js n=5000 scenario='reused-local-same-peer'        ***     34.34 %       ±5.45% ±7.18% ±9.22%

Be aware that when doing many comparisons the risk of a false-positive
result increases. In this case, there are 4 comparisons, you can thus
expect the following amount of false-positive results:
  0.20 false positives, when considering a   5% risk acceptance (*, **, ***),
  0.04 false positives, when considering a   1% risk acceptance (**, ***),
  0.00 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.

Edit: 🚀

[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.07%. Comparing base (2743045) to head (2b1f95e).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/crypto/crypto_ec.cc	87.50%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65615      +/-   ##
==========================================
+ Coverage   90.06%   90.07%   +0.01%     
==========================================
  Files         751      751              
  Lines      254917   254931      +14     
  Branches    48133    48132       -1     
==========================================
+ Hits       229580   229628      +48     
+ Misses      16493    16482      -11     
+ Partials     8844     8821      -23     

Files with missing lines	Coverage Δ
src/crypto/crypto_ec.h	16.66% <ø> (ø)
src/crypto/crypto_ec.cc	68.42% <87.50%> (+0.50%)	⬆️

... and 33 files with indirect coverage changes

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