- [x] add selection + copy support in the rows panel.
    - should be able to select/highlight an arbitrary rectangle (like vim visual block basically)
    - should be able to copy selection
    - copied data should be formatted nicely before inserting into the clipboard (system clipboard)
        - let's go for a markdown table format and csv format depending on copy action
    - should be able to copy with row names (`y` keybinding)
        - `ym` should copy to markdown format
        - `yc` should copy to csv format
    - should be able to copy without row names (`Y` keybinding)
        - `Ym` should copy to markdown format
        - `Yc` should copy to csv format
- [ ] add ability to update values from the row view