Add wasm support (#2199)

* 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

crates/nu-test-support/src/playground.rs

@@ -95,6 +95,7 @@ impl Playground {
         self
     }
 
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn symlink(&mut self, from: impl AsRef<Path>, to: impl AsRef<Path>) -> &mut Self {
         let from = self.cwd.join(from);
         let to = self.cwd.join(to);