Disable support for standardized algorithms

[baentsch]

Triggered by #609 this is to discuss whether oqsprovider should keep supporting standardized algorithms as and when they are available in built-in providers of openssl.

The code driving oqsprovider does not have the same quality and reliability as the code in openssl and therefore, oqsprovider should not make available algorithms when more reliable implementations are available.

Further, the goal of oqsprovider is to support prototyping and experimentation of novel PQC (e.g. in the NIST competition or other, not-yet standardized use cases), not do the same as standard PQC code.

[baentsch]

#613 provides another argument for dropping support for standardized algorithms:

the IETF LAMPS consensus is that private keys of all three of the NIST algorithms should be stored as seeds

Thus, their use now starts to deviate substantially from what NIST specified and what is still being used as key formats in the other/ongoing NIST competition that oqsprovider want to support, so bespoke code would have to be added for those algorithms. And that'd be pretty much lost work given that exactly these algorithms are bound to be available in openssl anyway.

[dstebila]

We talked in a previous meeting about continuing to support standardized algorithms where we have implementations with distinctive characteristics.