Filter out empty glob patterns to "glob" command (#6707)

* Filter out empty glob patterns

An empty argument to the "glob" command will now produce an empty result.
Working towards nushell/nushell#6653.

* Run `cargo fmt --all`

Just autoformatted the repo so that CI passes and we have a consistent code
format across modules.

* Treat empty glob argument as error

The glob command will now report an empty string argument as an error instead
of silently ignoring it.

See https://github.com/nushell/nushell/pull/6707#discussion_r993345013.

* Add tests for glob command

Two small tests for the glob command, one to check that the empty string errors
it, and another to sanity check the '*' glob, have been added.

* Rename glob sanity check star test

Co-authored-by: Kyle Anderson <kyle.anderson@uwaterloo.ca>

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

@@ -24,6 +24,7 @@ mod flatten;
 mod format;
 mod g;
 mod get;
+mod glob;
 mod group_by;
 mod hash_;
 mod headers;