Control channel: ui.dialog.confirm sends what OK sends (#1459)

OK runs a dialog's command with build_params(&d), which reshapes the
field values for several dialogs (the rule wrapper of cfQuick, the
delimiters list of Text to Columns, the columns of Remove Duplicates and
Subtotal, Data Validation's unused fields, Zoom presets, Series, Define
Name). ui.dialog.confirm passed the raw field values instead, so a
Highlight Cells rule confirmed over the control channel added nothing
and Text to Columns ignored the ticked delimiter.

Make build_params pub(crate) and use it from ui.dialog.confirm, say so
in the control protocol doc, and add tests driving the Greater Than and
Text to Columns dialogs over the control channel.

docs/control-protocol.md

@@ -31,7 +31,7 @@ Errors come back as `{"id": …, "ok": false, "error": "…"}`.
 | `ui.key` / `ui.text` | `{key, shift?, cmd?, alt?, ctrl?}` / `{text}` | Keyboard input (typing in the grid starts editing) |
 | `ui.edit.begin` / `ui.edit.text` / `ui.edit.commit` / `ui.edit.cancel` | `{text?}` / `{move?: down\|right\|up\|left\|none}` | Drive the cell editor |
 | `ui.ribbon` | `{tab}` | Switch ribbon tab |
-| `ui.dialog` / `ui.dialog.set` / `ui.dialog.confirm` / `ui.dialog.cancel` | `{name}` / `{field, value}` | Open, fill in and confirm dialogs |
+| `ui.dialog` / `ui.dialog.set` / `ui.dialog.confirm` / `ui.dialog.cancel` | `{name}` / `{field, value}` | Open, fill in and confirm dialogs; `confirm` runs the dialog's command with the same parameters as its OK button |
 | `ui.backstage` (via `engine.execute`) | `{page?: home\|new\|open\|info\|saveAs\|print\|export\|options\|close}` | Open the File tab's Backstage view on a page, or close it (`ui.inspect` reports the open page as `backstage`) |
 | `ui.screenshot` | `{path?}` | PNG of the window (base64 when no path). Animations are settled first: the picture shows the final state |
 | `ui.set` | `{dark?, formulaBar?, ribbonCollapsed?, animations?}` | UI preferences (`formulaBar` runs `view.formulaBar`) |