{Help,Song}Page: call FindSupport::Find() as coroutine

The method was converted to a coroutine by commit
dc0ed2f, but the HelpPage caller was
not adjusted, breaking searching on the help and song page.

Closes #154

NEWS

@@ -1,4 +1,5 @@
 ncmpc 0.52 - not yet released
+* fix searching on Help and Song page
 
 ncmpc 0.51 - (2024-09-23)
 * repaint main area after terminal was resized

src/HelpPage.cxx

@@ -309,9 +309,16 @@ HelpPage::OnCommand(struct mpdclient &c, Command cmd)
 		   search */
 		lw.SetCursorFromOrigin(0);
 
-	if (screen.find_support.Find(lw, *this, cmd)) {
-		SchedulePaint();
+	switch (cmd) {
+	case Command::LIST_FIND:
+	case Command::LIST_RFIND:
+	case Command::LIST_FIND_NEXT:
+	case Command::LIST_RFIND_NEXT:
+		CoStart(screen.find_support.Find(lw, *this, cmd));
 		return true;
+
+	default:
+		break;
 	}
 
 	return false;

src/SongPage.cxx

@@ -478,9 +478,16 @@ SongPage::OnCommand(struct mpdclient &c, Command cmd)
 	if (ListPage::OnCommand(c, cmd))
 		return true;
 
-	if (screen.find_support.Find(lw, *this, cmd)) {
-		SchedulePaint();
+	switch (cmd) {
+	case Command::LIST_FIND:
+	case Command::LIST_RFIND:
+	case Command::LIST_FIND_NEXT:
+	case Command::LIST_RFIND_NEXT:
+		CoStart(screen.find_support.Find(lw, *this, cmd));
 		return true;
+
+	default:
+		break;
 	}
 
 	return false;