Preview mode for report generation

[elasticmachine]

Original comment by @alexfrancoeur:

Many of our customers are surprised to see the layout of our PDF report after generating one. At the moment, we do not give them any control over this. As we begin to introduce features like LINK REDACTED, we could begin to provide previews of what their report would look like when exported to PDF, before saving and scheduling.

When discussed, Chrome's print preview UI is usually referenced

Initial implementation

• Preview mode would show how the PDF will look like when it's exported and generated
• It should also show where pagination occurs, possibly with a red line where the page ends

This will be a dramatic improvement to a users current experience of generating the report and allow them to proactively make improvements.

Subsequent phases

• I'd like to get to the point where where we become a bit more intelligent about pagination and rather than cutting off the report mid-visualization, we dynamically sort the report layout so that it fits the PDF.
• No matter how nicely we pre-package this report users will want to customize the layout as they see fit. It would be nice to have the ability to configure a "report layout" for a dashboard through this preview mode.

cc: @elastic/kibana-sharing, @snide

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServices)

[elasticmachine]

Pinging @elastic/kibana-reporting-services (Team:Reporting Services)

[tsullivan]

We could achieve this by separating out the screenshot and layout definition modules from Reporting, and use them to create a "one-off" screenshot that isn't connected to a report.

The solution is similar to #55622 (comment)

[ppisljar]

Thank you for contributing to this issue, however, we are closing this issue due to inactivity as part of a backlog grooming effort. If you believe this feature/bug should still be considered, please reopen with a comment.