add random commands (#366)

* feat: add random command

* feat: add bool sub-command

crates/nu-command/src/lib.rs

@@ -10,6 +10,7 @@ mod filters;
 mod formats;
 mod math;
 mod platform;
+mod random;
 mod shells;
 mod strings;
 mod system;
@@ -30,6 +31,7 @@ pub use filters::*;
 pub use formats::*;
 pub use math::*;
 pub use platform::*;
+pub use random::*;
 pub use shells::*;
 pub use strings::*;
 pub use system::*;