[Feature Request] Support Rancher Manager Add-on options

[JacieChao]

As the feature design discussion at https://github.com/cnrancher/autok3s/discussions/606:

• [x] Add autok3s add-ons CLI. Need to support creating add-ons by YAML file and set configurations.
• [x] Support --enable add-ons and set add-on configurations for autok3s create CLI.
• [x] Add add-ons management API.
• [x] Add default Rancher add-on.
• [x] Add add-ons management UI page.
• [x] Support select add-ons for the creating cluster page for each provider.
• [x] Add documentation for add-on feature

[ly5156]

1. add-ons list page
2. add-ons edit page
3. create add-ons page
4. select add-ons

[orangedeng]

Test passed with 0.9.0-rc3