A user-friendly system configuration page for apollo portal

[nobodyiam]

Is your feature request related to a problem? Please describe.
Currently, we have a system configuration page for apollo portal(as shown below). However, it's not user-friendly, e.g. there is no way to know what configurations are available to configure other than referring the configuration guide and it's also not possible to know how many configurations are already configured.

Describe the solution you'd like
Provide a user-friendly system configuration page that shows all the configurations available. For those config items already configured, the actual value is displayed. For those config items not configured(configView.memberOnly.envs below), we display it as another style, e.g. use gray background. e.g.

Key	Value	Comment	Operation
apollo.portal.envs	dev,pro	the env list	Edit
configView.memberOnly.envs	undefined	the envs that shows configurations only to its members	Add

Describe alternatives you've considered
I'm open to this and any ideas or suggestions are welcome.

Additional context

[nobodyiam]

assigned to student 姚苏桐, see https://summer-ospp.ac.cn/#/org/orgdetail/c4cc2271-6627-4965-a5ec-37d5ac3c0ad8/

[nobodyiam]

#4592