menu: close the mobile menu when a menu entry opens another tab of th…

[Greelan]

…e current page

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Describe the problem

On mobile, choosing a menu entry that points to another tab of the page already open (like VPN: WireGuard: Peers while on Instances) leaves the menu open over the page. Only the URL fragment changes, so no page load closes it; the page's own hashchange handler switches the tab underneath.

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Describe the proposed solution

This PR closes #navigation in that case, using the same check the Favorites code uses, for both MVC and legacy.

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Related issue

N/A