[FEATURE] Adjust styling for Finding details flyout

[phestecAMZN]

Is your feature request related to a problem?
This change would improve presentation of information by visually compartmentalizing it in a more clear way.

What solution would you like?
Adjust accordion style: - Add a top border to the first item- Put the accordion content in a grey container, see ISM’s policy detail page for sample: https://playground.opensearch.org/app/opensearch_index_management_dashboards#/policy-details?id=sample_policy

What alternatives have you considered?
A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?
Add any other context or screenshots about the feature request here.

[jovancacvetkovic]

@kamingleung are we going to add these changes to the flyouts? Also is there a way to have mocks or just use the link in a description? If we change these, should these be applied to rules and alerts too?

[jovancacvetkovic]

If we are going to do this, that perhaps we should think of some sort of template for the flyouts and use those for all flyouts across the app.

[kamingleung]

@jovancacvetkovic
This applies to the Findings flyout's Rules detail section.

What solution would you like?
Adjust the accordion for improving readability:

1. Add borders for each accordion entry like this:
   
2. Add a background and padding to the content inside the accordion like this (example from ISM):