* UX: Multichain: App header
* Export app header, provide required information, put feature flag in place
* Provide available data
* Implement account picker -- centered and opens account popover
* Remove backgrounds, use isUnlocked
* Fix placement of the global menu
* Show logo when unlocked
* Add selector for getting current network, provide props to AvatarNetwork and PickerNetwork
* Wire up the network menu to the header
* fixed ui for all the screens
* updated story for header
* fixed import and header settings
* updated lint error
* fixed tests
* updated header
* removed test
* updated snapshot test
* updated network menu
* updated changes
* removed comment from menu bar
* updated css
* updated test for network list menu
* updated stylesheet
* updated ButtonIcon import
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Co-authored-by: NidhiKJha <menidhikjha@gmail.com>
