Fix: page.resolve.then inline promise never resolving

[Smef]

When the <WhenVisible> component is used with preserveUrl: true the promise in page.resolve never actually resolves since history isn't being replaced and the callback is never called.

Example:

        <WhenVisible
            always
            :params="{
                data: {
                    page: nextPageToLoad,
                },
                only: ['paginatedData'],
                preserveUrl: true,
            }"
        >
            <template #fallback>
                <div>Loading...</div>
            </template>
            <div></div>
        </WhenVisible>

This will get stuck forever and never resolve.

This PR adjusts page.set when it returns page.resolve.then so that the promises it creates resolve without depending on the callback if preserveUrl is set to true. The callback is still used if preserveUrl is false, since the callback is queued normally in that scenario.