support table literal syntax in join right-table argument (#14190)

# Description

Makes `join` `right-table` support table literal notation instead of
parsing the column list (treated as empty data):

```diff
[{a: 1}] | join [[a]; [1]] a | to nuon
-[]
+[[a]; [1]]
```

Fixes #13537, fixes #14134

crates/nu-command/src/filters/join.rs

@@ -29,7 +29,7 @@ impl Command for Join {
         Signature::build("join")
             .required(
                 "right-table",
-                SyntaxShape::List(Box::new(SyntaxShape::Any)),
+                SyntaxShape::Table([].into()),
                 "The right table in the join.",
             )
             .required(