feat: allow users to pass more options to createFunction

[jaulz]

There are plenty of options that you can pass while creating a function: https://www.postgresql.org/docs/current/sql-createfunction.html

I think it's difficult to add them all to this library, so this is an attempt to let users pass arbitrary options (e.g. I am interested in defining the security options).

[Shinigami92]

I might not accept the current implementation-try, but will revisit this for v7.1