feat: Add shortcuts for stroke and background color picker (#3318)

* feat: Add shortcuts for opening stroke and background color picker

* Use App.tsx keydown handler

* only get selectedElements if applicable (perf)

* fix tests and snaps

* reuse `appState.openMenu`

Co-authored-by: dwelle <luzar.david@gmail.com>

src/components/HelpDialog.tsx

@@ -365,6 +365,14 @@ export const HelpDialog = ({ onClose }: { onClose?: () => void }) => {
                   label={t("labels.flipVertical")}
                   shortcuts={[getShortcutKey("Shift+V")]}
                 />
+                <Shortcut
+                  label={t("labels.showStroke")}
+                  shortcuts={[getShortcutKey("S")]}
+                />
+                <Shortcut
+                  label={t("labels.showBackground")}
+                  shortcuts={[getShortcutKey("G")]}
+                />
               </ShortcutIsland>
             </Column>
           </Columns>