Marking a group as 'pending deletion' should disable deletion action in all subgroups and projects

Problem

When a group is marked as pending deletion, deletion action is still available in all subgroups and projects.

This is misleading as when a group is marked for deletion, every resources under it should be read-only.

Proposal

We should align with the design guideline.

When to keep a feature visible

• When the user has access to a feature but it's not currently enabled. In this scenario, a feature may be visible but disabled. When a feature is disabled, there should be an explanation for why it's disabled, or controls that allow a user to enable or request access to the feature.
• When child-level settings are enabled from a parent level. In this scenario, a feature may be disabled or replaced with a read-only equivalent. There should be text explaining that the setting is configured at the parent level.

The user should have permission to "remove a group or project", but the action should be disabled due to its ancestor' state, or replaced with a read-only equivalent and explain the situation to user.