Defines validation to apply to new password (when creating an account or updating an existing account's password when using the NativeAuthenticationStrategy.
This is configured via the authOptions.passwordValidationStrategy property of
your VendureConfig.
InjectableStrategyValidates a password submitted during account registration or when a customer updates their password.
The method should resolve to true if the password is acceptable. If not, it should return false or
optionally a string which will be passed to the returned ErrorResult, which can e.g. advise on why
exactly the proposed password is not valid.