Add standalone MLKEM supported groups

[alexw91]

Issues:

N/A

Description of changes:

Adds opt-in support for standalone MLKEM SupportedGroup for all key sizes.

Call-outs:

None

Testing:

Unit tests. I also confirmed interoperability with Openssl v3.5.

# AWS-LC Server
$ ./build/tool/bssl s_server -curves MLKEM768:MLKEM1024:MLKEM512 -accept 44330 -debug

# Openssl 3.5 Client
$ openssl3 s_client -curves MLKEM512 -connect 127.0.0.1:44330 -debug
$ openssl3 s_client -curves MLKEM768 -connect 127.0.0.1:44330 -debug
$ openssl3 s_client -curves MLKEM1024 -connect 127.0.0.1:44330 -debug

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-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.75%. Comparing base (12b5dd5) to head (69855b4).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2589   +/-   ##
=======================================
  Coverage   78.75%   78.75%           
=======================================
  Files         646      646           
  Lines      111238   111302   +64     
  Branches    15712    15714    +2     
=======================================
+ Hits        87600    87657   +57     
- Misses      22945    22950    +5     
- Partials      693      695    +2     

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[WillChilds-Klein]

i pulled this PR down and confirmed the ML-KEM-only keyshare locally

[WillChilds-Klein]

minor nitpick: other struct literals have 2 newlines between , and {