crypto.bcrypt: allow very large passwords to be pre-hashed
bcrypt has a slightly annoying limitation: passwords are limited
to 72 characters. In the original implementation, additional characters
are silently ignored.
When they care, applications adopt different strategies to work around
this, in incompatible ways.
Ideally, large passwords should be pre-hashed using a hash function that
hinders GPU attackers, and the hashed function should not be deterministic
in order to defeat shucking attacks.
This change improves the developer experience by adding a very explicit
`silently_truncate_password` option, that can be set to `false` in
order to do that automatically, and consistently across Zig applications.
By default, passwords are still truncated, so this is not a breaking
change.
Add some inline documentation for our beloved autodoc by the way.