Improve behavior and documentation on saved object export version compatibility

[flash1293]

It's not possible to import saved objects from a more recent version of Kibana.
I've seen this popping op in the forums quite often. If a user attempts this they are met with a generic error message and I didn't find anything about this in the documentation.

I see the following ways to improve this and make Kibana easier to use:

• Show a clear error message in the import flyout if a user is attempting to import saved objects from a more recent version. The scenario should be easy enough to detect. Maybe even have a "try anyway and risk broken stuff" button (as it works fine quite often)? Not sure on the last one.
• Mention this in the documentation (or make it more prominent if it's in there already - I didn't find it) and explain the reasoning.
  • Will be fixed by [DOC] Clarify compatibility of Saved Objects across versions #63090

E.g. see https://discuss.elastic.co/t/kibana-import-visualization-fails-7-8-to-7-7/240806/3

[elasticmachine]

Pinging @elastic/kibana-docs (Team:Docs)

[elasticmachine]

Pinging @elastic/kibana-platform (Team:Platform)