Scope clearToasts to the dialog being closed

[Salvialf]

Problem

jeeDialog's close() unconditionally calls clearToasts(), which removes every toast currently displayed on the page, not just the ones related to the dialog being closed. Since there is a single shared toast container reused across the whole page, any toast shown right before closing a dialog (a common pattern: perform an action, then close the dialog) gets wiped out immediately.

Plugins have been working around this by manually closing the dialog before showing the success toast instead of the more natural order (see calendar/event.edit.js or ocpp/authorisations.js as examples).

Fix

clearToasts() now accepts an optional scope element. When provided, it only removes the toast container if it is currently a descendant of that scope, leaving toasts attached elsewhere (typically document.body) untouched. The main dialog's close() now passes itself as the scope, so it only cleans up toasts explicitly attached to it via attachTo.

All other existing call sites (page navigation, notification center, legacy jQuery shim) keep clearing every toast since they call clearToasts() without a scope, so their behavior is unchanged.