* move basic_shell_manager to nu-engine
* move basic_evaluation_context to nu-engine
* fix failing test in feature which commands/classified/external.rs
We split off the evaluation engine part of nu-cli into its own crate. This helps improve build times for nu-cli by 17% in my tests. It also helps us see a bit better what's the core engine portion vs the part specific to the interactive CLI piece.
There's more than can be done here, but I think it's a good start in the right direction.
* Add args in .nurc file to environment
* Working dummy version
* Add add_nurc to sync_env command
* Parse .nurc file
* Delete env vars after leaving directory
* Removing vals not working, strangely
* Refactoring, add comment
* Debugging
* Debug by logging to file
* Add and remove env var behavior appears correct
However, it does not use existing code that well.
* Move work to cli.rs
* Parse config directories
* I am in a state of distress
* Rename .nurc to .nu
* Some notes for me
* Refactoring
* Removing vars works, but not done in a very nice fashion
* Refactor env_vars_to_delete
* Refactor env_vars_to_add()
* Move directory environment code to separate file
* Refactor from_config
* Restore env values
* Working?
* Working?
* Update comments and change var name
* Formatting
* Remove vars after leaving dir
* Remove notes I made
* Rename config function
* Clippy
* Cleanup and handle errors
* cargo fmt
* Better error messages, remove last (?) unwrap
* FORMAT PLZ
* Rename whitelisted_directories to allowed_directories
* Add comment to clarify how overwritten values are restored.
This improves incremental build time when working on what was previously
the root package. For example, previously all plugins would be rebuilt
with a change to `src/commands/classified/external.rs`, but now only
`nu-cli` will have to be rebuilt (and anything that depends on it).