Extract common store from operations dashbord

What does this MR do?

Moves the store used as part of the operations dashboard to vue_shared, and uses it with the environments dashboard, as part of implementing #3713 (closed).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

closes #11443 (closed)