fips: continuous random bit generator tests

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/25526)