fips: continuous random bit generator tests

For FIPS 140-3 the continuous tests specified in SP 800-90B need to be
included on the output of any entropy source.

They are impleme

fips: continuous random bit generator tests

For FIPS 140-3 the continuous tests specified in SP 800-90B need to be
included on the output of any entropy source.

They are implemented here as a replacement for the primary DRBG in the FIPS
provider. This results in a setup that looks like this:

+-------------+
| |
| Seed Source |
| |
+------+------+
|
|
v
+-------------+
| |
| CRNG Test |
| |
++----------+-+
| |
| |
v v
+--------------+ +--------------+
| | | |
| Public DRBG | | Private DRBG |
| | | |
+--------------+ +--------------+

An additional benefit, that of avoiding DRBG chains, is also gained.
The current standards do not permit the output of one DRBG to be used
as the input for a second (i.e. a chain).

This also leaves open the future possibility of incorporating a seed
source inside the FIPS boundary.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25415)

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