[Enhancement] Aggregated Enhancement from v0.5.1

[orangedeng]

1. UI enhancement
   • [x] #500
   • [x] No require mark in create cluster options.
   • [x] Credential options should be input before all instance option because UI needs to fetch info with cloud credentials.
   • [x] There is no style difference between the editable dropdown and the normal dropdown in create cluster options. It could be confusing when some options support customization.
2. backend/design enhancement
   • [ ] Templates and related function should be supported in CLI.
   • [x] #499
   • [ ] Maybe we can use name to be the unique key instead of provider + name. And also support cluster-name-override options for each provider to override the default cluster name.
   • [ ] Support HTTP proxy environment variables for running k3s install script.
   • [ ] Support downloading kube-explorer from Github/mirror-site when binary not found in command.
   • [x] #448
   • [ ] #440
   • [ ] Delete node by instance ID instead
   • [ ] #414
3. provider enhancement
   • [ ] #270
   • [ ] Linode provider support

[ly5156]

UI Enhancement

1. editable combobox component adds edit icon

[ly5156]

1. add require mark

[ly5156]

ui demo: