Always auto-indent in block-wise mode when pasting

If the text was copied outside of Zed, so the original indent column is unknown,
then act as if the first line was copied in its entirety.

crates/editor/src/editor.rs

@@ -2020,7 +2020,9 @@ impl Editor {
                     old_selections
                         .iter()
                         .map(|s| (s.start..s.end, text.clone())),
-                    Some(AutoindentMode::EachLine),
+                    Some(AutoindentMode::Block {
+                        original_indent_columns: Vec::new(),
+                    }),
                     cx,
                 );
                 anchors