Rearrange resource policy setting

[lizable]

※ NOTICE: Only admin and super-admin users have an access to the Users page.

Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] 기능 요청이 특정 문제에 연관된 것이라면 여기에 그 문제를 설명해주세요. Resource policy affects the resources that the user can allocate in the session. In terms of admin(including superadmin), there are several things that seem awkward.

• Case 1. updating resource policy of users When the admin user tries to update one of the users' resource policy, It is only available in Credentials tab, not in Users tab.
• Case 2. removing resource policy When the admin user tries to remove one of resource policies, there must be no users(credentials) are assigned to the resource policy. The problem is that there's no quick way to see whether any user is assigned or not. The only way to find out is to check every credential in the Credentials Tab, both active and inactive. It will become cumbersome when there are more than 10 users(credentials) in the list.

Describe the solution you'd like A clear and concise description of what you want to happen. 어떤 기능이 있으면 좋겠는지 자세히 설명해주세요. To provide an intuitive user experience, there are several things to be updated. a. list every user assigned in each resource policy and support transferring to another resource policy at once. b. show resource policy and access key(credential) in pair at the user details dialog.

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered. 혹시 다른 대안들을 생각해본 적이 있다면 함께 적어주세요. If things are hard to cram in the current UI, showing them in a new panel could be an alternative solution.

Additional context Add any other context or screenshots about the feature request here. 기능 요청에 대해 보다 잘 이해할 수 있는 다른 맥락을 기술해주세요. To see, current problem, see the documentation of the latest Backend.AI GUI Console.