compare key created by public and by private material

[petrovr]

This is quite tricky area, full with implementation defects. This is reason to open issue as feature request.

OpenSSL default provider succeed to compare ML-DSA keys created by public and by private material.
The same code fail if ML-DSA keys are managed by OQS provider.

[petrovr]

The sample code was uploaded to another issue, see #745 (comment) , function test_pkey_eq.