ec/suite_b: Move scalar multiplication functions from C to Rust.

[briansmith]

[codecov[bot]]

Codecov Report

:x: Patch coverage is 92.30769% with 4 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 96.66%. Comparing base (1bb94b3) to head (04d552b).

Files with missing lines	Patch %	Lines
src/arithmetic/inout.rs	88.88%	1 Missing and 1 partial :warning:
src/ec/suite_b/ops/p256.rs	95.00%	1 Missing :warning:
src/ec/suite_b/ops/p384.rs	90.90%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2692      +/-   ##
==========================================
- Coverage   96.70%   96.66%   -0.05%     
==========================================
  Files         187      186       -1     
  Lines       20116    20152      +36     
  Branches      513      513              
==========================================
+ Hits        19454    19479      +25     
- Misses        558      566       +8     
- Partials      104      107       +3     

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