[DRAFT] Flip to new randomness generation backend and remove the existing

[torben-hansen]

Description of changes:

This PR removes the existing randomness generation and replaces it with the new one. It does a number of things to do that:

• removes "unsafe buffering" mode. This is not a thing in the new implementation and was never used.
• move rdrand implementation to the entropy source implementation file
• removes the ability to specify the "entropy source" at compile time. The flag is retained by build backwards compatibility. There is only a single (validable) entropy source left, and that is jitter entropy. (other sources are used, but not validatable).
• passive entropy is removed completely.
• the PRNG model test is disabled until I fix it.
• RAND_bytes_with_user_prediction_resistance() is introduced as a public API. It replaces the internal RAND_bytes_with_additional_data().
• correct sandbox test to account for getrandom usage.

Call-outs:

Future PRs will expand tests and re-enable the PRNG model test.

Testing:

Existing testing now uses the new randomness generation backend.

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

Attention: Patch coverage is 92.89941% with 12 lines in your changes missing coverage. Please review.

Project coverage is 78.78%. Comparing base (19e9b93) to head (f2aed9d).

Files with missing lines	Patch %	Lines
crypto/fipsmodule/rand/rand.c	95.51%	7 Missing ⚠️
crypto/fipsmodule/rand/entropy/entropy_sources.c	54.54%	5 Missing ⚠️

Additional details and impacted files

@@                    Coverage Diff                    @@
##           randomness_generation    #2147      +/-   ##
=========================================================
+ Coverage                  78.73%   78.78%   +0.04%     
=========================================================
  Files                        608      606       -2     
  Lines                     102800   102471     -329     
  Branches                   14585    14532      -53     
=========================================================
- Hits                       80944    80729     -215     
+ Misses                     21144    21042     -102     
+ Partials                     712      700      -12     

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