Test granularity, distribution, and inner range of crypto_rand* functions

In legacy/trac#23061 (moved), we added tests for crypto_rand_double() that test:

• granularity: low bits being non-zero,
• distribution: some values above and below half, and
• inner range: mock crypto_rand() and generate lowest and highest valid results.

We should do the same for:

• crypto_rand()
• crypto_rand_int()
• crypto_rand_int_range()
• crypto_rand_uint64()
• crypto_rand_uint64_range()
• crypto_rand_time_range()
• crypto_rand_hostname()