Add Delete button in visualization editor

[merlinz01]

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

Currently you have to navigate to the list of visualizations, check the box of the one you want to delete, and hit Delete Visualization.
The Delete Visualization button only appears when one or more check boxes is selected; it appears nowhere else AFAIK. You have to figure out how to get to where you can delete it, vs. hit a handy Delete button.

Describe the solution you'd like

A nice "Delete" button in the visualization editor toolbar alongside the Save button.

Describe alternatives you've considered

Maybe that would make it too easy to delete a visualization that is referenced in many different dashboards.
However, in my opinion, when a user confirms deletion, it generally means they understand the consequences.

Additional context

I am using Opensearch Dashboards 2.12.0.