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.
* Working towards a PoC for wasm
* Move bson and sqlite to plugins
* proof of concept now working
* tests are green
* Add CI test for --no-default-features
* Fix some tests
* Fix clippy and windows build
* More fixes
* Fix the windows build
* Fix the windows test
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).
