[Dashboards] Separate export from share menu

[ghudgins]

Describe the feature

Create an independent export menu for export operations in Dashboards, Discover, and Lens.

Use case for this feature

When Elastic has lots of export options for off platform sharing
I need a dedicated menu
So I can more easily review those options independently from on-platform sharing

Notes:

From a discussion with @nickpeihl

• Create an export plugin menu
• Move logic from share menu to populate export menu (don't render if there are no options, register options based on license level)
• Remove export options from share menu
• Remove or move warning functionality to intercept modal with confirmation

This may require splitting the existing "share" plugin into two plugins ("@kbn/export-plugin" and "@kbn/share-plugin"). The reporting logic (CSV, PDF, PNG) moves from the share plugin to the export plugin. The "share" plugin keeps the URL locator service with the possibility of future services such as "share to space(s)", "share with user/team", etc.

Design:

Figma

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[ThomThomson]

Are we anticipating also making the wording change from the figma to Exit edit instead of Switch to view mode?