[Reporting/Design] Add a new Export menu item & update Reporting table

[ryankeairns]

Describe the feature:
In an effort to raise awareness of Reporting capabilities, we discussed a couple of changes that better align with user expectations:

Add 'Export' menu item

Split out export-related actions from the Share menu and place then in a new top-level 'Export' menu item. This would contain links like 'Export to CSV', 'Export to PNG', 'Export to PDF', etc., while the Share menu would retain links for 'Get embed code' and 'Get permalink'.

• Add 'Export' menu item to Discover
• Add 'Export' menu item to Dashboard

Marvel prototype

👉 https://marvelapp.com/8g51848/screen/58300225

Preview snapshots from Marvel prototype 👆

Improve the Reporting table

Update the Management > Reporting table view to more clearly present information about completed reports. Changes include:

• Use application icon (instead of text) to identify source and save horizontal space
• Make the report title/name clickable
• Use an icon to convey status and place it next to the related datetime value
• Display the report format (CSV, PNG, PDF), and make it clickable
• Make the column headers sortable

Marvel prototype

👉 https://marvelapp.com/8g51848/screen/58293451

Preview snapshots from Marvel prototype 👆

[tsullivan]

I love all the Reporting table improvements!

[tsullivan]

The UI changes proposed here would solve the related issue: #45053

[joelgriffith]

I'm definitely excited to get this in

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[tsullivan]

NOTE: The changes to the Export menus are under the ownership of the apps that want to integrate with Reporting. On the UI side, the Reporting devs manage just the job listing of the reports.