Refactor nu-cli/env* (#3041)

* Revert "History, more test coverage improvements, and refactorings. (#3217)"

This reverts commit 8fc8fc89aa.

* Add tests

* Refactor .nu-env

* Change logic of Config write to logic of read()

* Fix reload always appends to old vars

* Fix reload always takes last_modified of global config

* Add reload_config in evaluation context

* Reload config after writing to it in cfg set / cfg set_into

* Add --no-history to cli options

* Use --no-history in tests

* Add comment about maybe_print_errors

* Get ctrl_exit var from context.global_config

* Use context.global_config in command "config"

* Add Readme in engine how env vars are now handled

* Update docs from autoenv command

* Move history_path from engine to nu_data

* Move load history out of if

* No let before return

* Add import for indexmap

crates/nu-cli/src/line_editor.rs

@@ -202,7 +202,7 @@ pub fn configure_rustyline_editor(
 
 #[cfg(feature = "rustyline-support")]
 pub fn nu_line_editor_helper(
-    context: &mut EvaluationContext,
+    context: &EvaluationContext,
     config: &dyn nu_data::config::Conf,
 ) -> crate::shell::Helper {
     let hinter = rustyline_hinter(config);
@@ -224,7 +224,7 @@ pub fn rustyline_hinter(
     Some(rustyline::hint::HistoryHinter {})
 }
 
-pub fn configure_ctrl_c(_context: &mut EvaluationContext) -> Result<(), Box<dyn Error>> {
+pub fn configure_ctrl_c(_context: &EvaluationContext) -> Result<(), Box<dyn Error>> {
     #[cfg(feature = "ctrlc")]
     {
         let cc = _context.ctrl_c.clone();