Outline: Shift+click to select the symbol's full range

[Copilot]

Adds Shift+click on an Outline view item as a shortcut for selecting the symbol's full range (function body, variable declaration, etc.) in the editor. Previously, this was only available via double-click, which also moves focus to the editor.

Changes

• outlinePane.ts: In the tree's onDidOpen handler, detect Shift+click via dom.isMouseEvent(e.browserEvent) && e.browserEvent.shiftKey and pass select=true to IOutline.reveal(...) for both double-click and Shift+click. The flag flows through DocumentSymbolsOutline.reveal to select symbol.range instead of collapsing to the symbol's selection range. No conflict with tree multi-select since the outline tree sets multipleSelectionSupport: false.

const isDoubleClick = e.browserEvent?.type === 'dblclick';
const isShiftClick = dom.isMouseEvent(e.browserEvent) && e.browserEvent.shiftKey;
...
await newOutline.reveal(e.element, e.editorOptions, e.sideBySide, isDoubleClick || isShiftClick);