Display the current coverage data for each selected project

What does this MR do?

Related to #215135 (closed)

Add the table for displaying the test coverage for selected projects from a group. This uses a temporary client resolver while we wait for the backend work to be finished.

This feature is behind a feature flag, so no changelog is needed.

Screenshots

Empty State

Loading State

Table

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• Separation of EE specific content

Availability 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
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done