[Expressions] Add support of the saved search embeddable by the kibana_context function

[dokmic]

Summary

Update the kibana_context function to accept the savedSearch function output in the savedSearchId argument.

Resolves #67901.

Checklist

• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: f4d712a
• Storybooks Preview

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
canvas	534.7KB	534.8KB	+80.0B
data	839.6KB	839.8KB	+215.0B
total			+295.0B

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream