Arrow direction in pretty-printed stacks

### Related Problem I looked through issues in case there was already a discussion about it, but didn't manage to find anything - please point me to it if there was one. Currently, the printed report looks something like this ``` external error ├╴at src/main.rs:29:20 │ ├─▶ intermediate error │ ╰╴at src/main.rs:21:21 │ ╰─▶ internal error ╰╴at src/main.rs:13:23 ``` This seems a bit confusing from the design perspective - it implies that there is some data flow going on from the external error to internal ones. ### Proposed Solution I wonder, wouldn't it be more intuitive if it looked something like this: ``` external error ╰╴at src/main.rs:29:20 ▲ └── intermediate error ┌─▶ ╰╴at src/main.rs:21:21 │ ╰── internal error ╰╴at src/main.rs:13:23 ``` or this: ``` external error ╰╴at src/main.rs:29:20 ▲ └── intermediate error ▲ ╰╴at src/main.rs:21:21 │ ╰── internal error ╰╴at src/main.rs:13:23 ``` ### Alternatives _No response_ ### Additional context _No response_