MudPopover: Log instead of throw when no provider is in the render scope

[danielchalmers]

When a popover-based component (MudDatePicker, MudDateRangePicker, MudSelect, MudMenu, ...) initializes but no MudPopoverProvider is subscribed in its render scope, PopoverService.CreatePopoverAsync threw an InvalidOperationException from the component's OnInitializedAsync.

In a Blazor Web App with per-page interactivity this is a common misconfiguration: the providers sit in the static MainLayout while the components run on an interactive page, so the circuit-scoped PopoverService has no subscribed provider. Throwing from a lifecycle method during the render batch tears down the circuit mid-render, and the sibling components' pending renders then fault with a cryptic ObjectDisposedException (ArrayBuilder.GrowBuffer -> RenderTreeDiffBuilder.InsertNewFrame -> Renderer.ProcessRenderQueue) — which is what users actually see, hiding the real cause.

This converts the fatal throw into a single, actionable error log and keeps the popover holder registered, so the app stays usable and the popover renders if a provider becomes present in the scope. The real cure for an affected app is still to place the providers in the same interactive render mode as the components; the logged message and the installation docs now spell this out.

Same root cause as #11168, #12277, #12283.

Before, the circuit crashes:

fail: ...Circuits.CircuitHost[111] Missing <MudPopoverProvider />
fail: ...Circuits.CircuitHost[111] System.ObjectDisposedException: Cannot access a disposed object.
   at ArrayBuilder`1.GrowBuffer ... at Renderer.ProcessRenderQueue

After, the app keeps running with one actionable log:

fail: MudBlazor.PopoverService[0] Missing <MudPopoverProvider /> in the active render scope, so popovers
cannot be displayed. Add <MudPopoverProvider /> within the same interactive render mode as the components
that use it: in your layout for global interactivity, or on each page for per-page interactivity.
See https://mudblazor.com/getting-started/installation#manual-install-add-components

Fixes #11887

[danielchalmers]

[versile2]

LGTM.