Integrated Alerting: Show rule details for items in Alert Rules list

User Story:

As a PMM admin user, I want to be able click on a  icon in the alert rule summary to have more details about the alert rule. The table row would expand to showing more details.

Acceptance Criteria:

• There is a ↓ icon in the Name column;
• clicking on the icon, a new row appears under the one on which the icon was clicked;
• the newly opened row spans for the whole width of the table and contains the details to be shown (TBD);

Implementation Details:

• code and PRs get pushed to percona-platform/grafana repository
• test coverage
• honor light/dark mode