Add standard component for notifications (BBBToast)

[Arthurk12]

Is your feature request related to a problem? Please describe.
bigbluebutton-html5 has its own hand-rolled toast notification implementation (imports/ui/services/notification + imports/ui/components/common/toast, on top of react-toastify) that isn't part of this shared component library. It's used in 44+ files across the client (errors, status changes, chat push alerts, recording/breakout/screenshare notices, plugin-triggered notifications, etc.), so it's a core, high-reuse UI primitive that belongs here instead of being duplicated/reimplemented per consuming app.

Describe the solution you'd like
A BBBToast component (the presentational notification card) with a props surface derived from every current call site in bigbluebutton-html5:

Property	Type	Default	Description
message	React.ReactNode	—	Primary text/title of the notification.
type	'default' | 'info' | 'success' | 'warning' | 'error'	'default'	Visual variant; drives the default icon and color.
icon	React.ReactNode | string | false	icon matched to type	Custom icon, or false to hide it entirely.
content	React.ReactNode	—	Optional secondary content (description, links, action buttons) shown below a separator.
showSeparator	boolean	true	Shows/hides the divider between message and content.
small	boolean	false	Compact variant for space-constrained placements.
disablePointer	boolean	true	Whether the toast shows a pointer cursor (i.e. reads as clickable).
onClick	() => void	—	Click handler for the whole toast (e.g. open a related chat/panel).
actionLabel	string	—	Label for an optional secondary action button rendered in the toast.
onActionClick	() => void	—	Handler for the action button (current impl only supports opening a URL via helpLink/helpLabel; generalizing to a callback is recommended).
autoClose	number | false	5000	Auto-dismiss delay in ms, or false to persist until manually dismissed.
closeButton	boolean	true	Shows/hides the close (X) button.
onRequestClose	() => void	—	Callback fired when the toast is dismissed.
id	string	auto-generated	Custom id, for de-duplication or programmatically updating/dismissing a specific toast.

Describe alternatives you've considered
Keeping the toast logic duplicated in each consuming app (current state) — leads to visual drift between BBB's own client and other apps built on this component library.

Affected component(s)
New component: BBBToast.
Proposed API / Usage Example

import { BBBToast } from '@bigbluebutton/bbb-ui-components-react';

<BBBToast
  type="warning"
  message="You are muted"
  content="Click to unmute"
  autoClose={5000}
  onClick={() => unmute()}
/>

Screenshots or mockups

Additional context

• Current implementation reference: bigbluebutton-html5/imports/ui/services/notification/index.js and bigbluebutton-html5/imports/ui/components/common/toast/component.jsx.
• The BBB plugin SDK already exposes an equivalent, stable public contract for third-party plugins (bigbluebutton-html-plugin-sdk's SendNotificationCommandArguments: message, icon, type, options: { helpLabel, helpLink, autoClose }, content, small), which is a good cross-check for the prop set above.
• bigbluebutton-html5 currently depends on react-toastify for stacking/positioning/auto-dismiss; worth deciding whether BBBToast should stay presentation-only (consumer wires up their own toast engine, like BBBModal does with open/onRequestClose) or whether the library should also ship a toast-engine/container.