Make stream info visible to users in describe (#7589)

Closes #7581.

After this PR, `describe` shows `(stream)` next to input that arrived at
`describe` as a `ListStream`:
```bash
〉ls | describe
table<name: string, type: string, size: filesize, modified: date> (stream)
〉[1 2 3] | each {|i| $i} | describe
list<int> (stream)
```

`describe` must collect all items of the stream to display type
information for lists and tables. If users need to avoid collecting
input, they can use the `-n`/`--no-collect` flag:

```bash
〉[1 2 3] | each {|i| $i} | describe --no-collect
stream
```

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

@@ -76,7 +76,7 @@ fn gets_last_row_as_list_when_amount_given() {
             "#
     ));
 
-    assert_eq!(actual.out, "list<int>");
+    assert_eq!(actual.out, "list<int> (stream)");
 }
 
 #[test]