Fix transpose input/output types (#9842)

# Description

As the typechecker doesn't currently support having the same input type
but two different output types, collapse the `transpose` input/output
signatures for now so that we don't mistakenly think that when given a
`table` a `table is always returned.

fixes https://github.com/nushell/nushell/issues/9710

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

@@ -27,8 +27,7 @@ impl Command for Transpose {
     fn signature(&self) -> Signature {
         Signature::build("transpose")
             .input_output_types(vec![
-                (Type::Table(vec![]), Type::Table(vec![])),
+                (Type::Table(vec![]), Type::Any),
-                (Type::Table(vec![]), Type::Record(vec![])),
                 (Type::Record(vec![]), Type::Table(vec![])),
             ])
             .switch(

src/tests/test_type_check.rs

@@ -86,3 +86,11 @@ fn record_subtyping_3() -> TestResult {
         "expected",
     )
 }
+
+#[test]
+fn transpose_into_load_env() -> TestResult {
+    run_test(
+        "[[col1, col2]; [a, 10], [b, 20]] | transpose -i -r -d | load-env; $env.a",
+        "10",
+    )
+}