Refactor/config commands (#3265)

* Use ctx.configs in all config commands

* Remove all setting/accessing of  vars.("config-path")

* Add tests

* Add comment

* Reload cfg on remove

* Hypocratic ws change

* Use history_path in hist_or_default

* Make clippy happy

* Fix rebase stuff

* Fix clippy lint

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

@@ -4,6 +4,7 @@ mod append;
 mod cal;
 mod cd;
 mod compact;
+mod config;
 mod cp;
 mod def;
 mod default;