[Enhancement] Redesign global header

Is your feature request related to a problem? Please describe. We’ve had some requests to remove the top bar, as well as making it easier to change the top logo. This is a meta issue that covers redesigning the global header.

See: https://discuss.opendistrocommunity.dev/t/change-top-left-elastic-logo-on-opendistro-kibana/5436

Describe the solution you’d like

The initial proposal is to collapse the current stacked header into a single one.

The UX team is exploring the responsive behavior in the top bar, and will add additional guidance here for how to handle the user menu, tenants, and cases where there are additional action menus (Such as the Full screen | Share | Clone | Reporting | Edit actions in the Dashboard plugin.)

Additionally, we’d like to explore uploading an SVG in advanced settings in order to make it easy to change the logo in the header.

Additional context This issue was originally raised from the OpenSearch forum

Related forum posts:

• https://discuss.opendistrocommunity.dev/t/change-top-left-elastic-logo-on-opendistro-kibana/5436
• https://discuss.opendistrocommunity.dev/t/opensearch-dashboards-logo-feels-wrong/6510

[jgough]

I made a comment in 2019 about how the Kibana header was getting more and more progressively complex with each successive release. Elastic does not seem interested in changing things though. Hoping things can be simplified here in Opensearch Dashboards.

[robcowart]

@kgcreative I like the simple bar. This is closer to the earlier Kibana 7 styling before the screen real estate wasting top bar with useless search box was added (sorry… I am a bit opinionated on this).