Add support for parsing ECPKParameter PEM files

Issues:

Addresses CryptoAlg-1715

Description of changes:

Ruby depends on reading/writing PEM files that are defined as EcpkParameters (See RFC 3279 for more details).EcpkParameters actually just refer to potential different ways of serializing EC Groups and we already have basic support for this. OpenSSL's implementation of d2i/i2d_ECParameters actually calls d2i/i2d_ECPKParameters internally.

I've borrowed some of the logic for d2i/i2d_ECParameters and worked them into the new functions. Apparently we only support parsing named curves or explicitly encoded versions of them, so I've documented that and followed the same pattern. No new parsing logic has been added for EC_GROUPs.
We do not support writing custom curves to any ASN.1 output and this PR continues that trend.

Call-outs:

Code change in crypto/pem/pem_lib.c was taken from OpenSSL: https://github.com/openssl/openssl/commit/205957405d08ef199e6ab654e333a627bbca9ccc It was worth taking, so the call to PEM_write_bio could be cleaner.

Testing:

Tests for named curves and a explicitly encoded versions of P256. The same PEM file works fine with OpenSSL as well
We don't support writing custom curves, so I have a test to make sure.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

Codecov Report

Attention: Patch coverage is 81.03448% with 11 lines in your changes missing coverage. Please review.

Project coverage is 78.26%. Comparing base (21c5e48) to head (0e319eb).

Files	Patch %	Lines
crypto/ec_extra/ec_asn1.c	57.89%	8 Missing :warning:
crypto/pem/pem_all.c	86.95%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1670 +/- ## ======================================= Coverage 78.26% 78.26% ======================================= Files 567 567 Lines 95238 95290 +52 Branches 13673 13678 +5 ======================================= + Hits 74535 74579 +44 - Misses 20109 20115 +6 - Partials 594 596 +2 ```

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