Refactor: introduce general operate commands to reduce duplicate code (#6879)

* make format filesize more flexible

* make code simpler

* finish refactor on bytes commands

* finish refactor on str commands

* fimplify code

* rename from column_paths to cell_paths

crates/nu-command/src/lib.rs

@@ -14,6 +14,7 @@ mod filters;
 mod formats;
 mod generators;
 mod hash;
+mod input_handler;
 mod math;
 mod misc;
 mod network;