Implement histogram command (#5518)

* finish histogram

* adjust comment

* add test for histogram

* add Date to test

* move hashable value back inside chart package

crates/nu-command/src/lib.rs

@@ -1,3 +1,4 @@
+mod charting;
 mod conversions;
 mod core_commands;
 mod date;
@@ -21,6 +22,7 @@ mod strings;
 mod system;
 mod viewers;
 
+pub use charting::*;
 pub use conversions::*;
 pub use core_commands::*;
 pub use date::*;