Update CI (#4445)

* Add different features combinations

* Specify styles manually

* Fix args

* Fix typo

* Let other CI jobs finish if one fails

* Fix unused symbols without plugin feature

* Put "which" tests behind "which" feature

* Add Python virtualenv job

* Oops forgot git command

* Install Nushell in virtualenv tests

* Add names to steps; Test v.env in separate step

* cd into virtualenv

* Do not run on Python 2.7

* Build Nushell after formatting and clippy checks

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

@@ -61,6 +61,7 @@ mod touch;
 mod uniq;
 mod update;
 mod where_;
+#[cfg(feature = "which")]
 mod which;
 mod with_env;
 mod wrap;