support filesize arguments in random binary/chars (#14068)

Closes #13920

# User-Facing Changes

`random binary` and `random chars` now support filesize arguments:

```nushell
random binary 1kb
random chars --length 1kb
```

crates/nu-command/tests/commands/random/mod.rs

@@ -1,3 +1,4 @@
+mod binary;
 mod bool;
 mod chars;
 mod dice;