[UX] Improve terminology and layout of the "Stack Management" page

[joshuarrrr]

Is your feature request related to a problem? Please describe.

The copy and naming of the stack management page are not very useful. "Stack Management" sound like it's mostly a place to manage infrastructure, or maybe the OpenSearch Cluster. But it's really the place to manage all the global configurations and settings of OpenSearch Dashboards.

Some quibbles I have:

1. In the screenshot, 2.5.0 is the version of OpenSearch dashboards. But "Welcome to Stack Management 2.5.0" makes it sound like it's the version of stack management
2. The description is "Manage your indices, index patterns, saved objects, OpenSearch Dashboards settings, and more." - How exactly does stack management allow the managing of indices? Each of the other listed items have a corresponding entry in the left menu
3. What's the point of this screen - could we have a better default? Having a message like A complete list of apps is in the menu on the left. seems to acknowledge that the layout is weird - why shove all the useful navigation links off to the side? Does a left-menu even make sense for this management app?

Describe the solution you'd like

I'd like to streamline the management app, so that you can actually do something from the home screen, rather than just choose from a list of links to click. And I suggest it should have a different name.

Describe alternatives you've considered

I think there are lots of potential directions we could go with settings/configurations/management - maybe not all of the current management pages even belong together. But I'd like to use this issue to kick-start a discussion and brainstorming.

Additional context

Other loosely related management issues:

#731
#981
#1168
#3272

[joshuarrrr]

cc @kgcreative, because I think you already have some thoughts around this.

[kgcreative]

cc @kamingleung, @dagneyb, @mnkugler, who are working on this