random: Use modern Windows randomness functions

The old randomness API has been deprecated and may be removed soon.[^1]

For reference on `BCryptGenRandom`, see: https://learn.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom.

`STATUS_SUCCESS`[^2] gets defined here since including `ntstatus.h` is
more trouble than it's worth. [^3]

[^1]: https://learn.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-cryptacquirecontextw & https://learn.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-cryptgenrandom
[^2]: https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-erref/596a1078-e883-4972-9bbc-49e60bebca55
[^3]: See https://github.com/bitcoin-core/secp256k1/blob/70f149b9a1bf4ed3266f97774d0ae9577534bf40/examples/examples_util.h#L19-L28

contrib/guix/symbol-check.py

@@ -153,7 +153,8 @@ MACHO_ALLOWED_LIBRARIES = {
 }
 
 PE_ALLOWED_LIBRARIES = {
-'ADVAPI32.dll', # security & registry
+'ADVAPI32.dll', # legacy security & registry
+'bcrypt.dll', # newer security and identity API
 'IPHLPAPI.DLL', # IP helper API
 'KERNEL32.dll', # win32 base APIs
 'msvcrt.dll', # C standard library for MSVC