Standardized the -rand flag and added a new one:
    -rand file...
            Always reads the specified files
    -writerand file
            Always writes to the file on exit

For apps that use a config file, the RANDFILE config parameter reads
the file at startup (to seed the RNG) and write to it on exit if
the -writerand flag isn't used.

Ensured that every app that took -rand also took -writerand, and
made sure all of that agreed with all the documentation.

Fix error reporting in write_file and -rand
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/3862)