Double/Triple clicking and dragging should select words/lines

Double click a word but continue holding the mouse down and drag it across the document.
Right now, this will cancel the word-selection and continue a regular char-wise selection. Other editors continue with a word-wise selection. For triple-clicks this should do a line-wise selection.

Changes are needed here to keep the click counter state into a drag:
https://github.com/microsoft/edit/blob/b008570afc0c4c6cef7ba0335d407139a47c8e24/src/tui.rs#L554-L611

And here to continue to change the word-selection mode during dragging:
https://github.com/microsoft/edit/blob/b008570afc0c4c6cef7ba0335d407139a47c8e24/src/tui.rs#L2188-L2206

Read the click handling in src/tui.rs around lines 554-611, then follow the dragging selection logic around lines 2188-2206. Preserve double- and triple-click state during dragging so word-wise and line-wise selection continue across the document, and verify that ordinary character-wise dragging remains unchanged.

Written by the indexing model from the issue text.