Add storage for additional information about instance added by user on console.

[fabian4]

What is the feature you want to add?

• add storage for additional information about instance added by user on console.

Why do you want to add this feature?

• issue: https://github.com/polarismesh/polaris/issues/790

How to implement this feature?

• [x] 1. database struct design (mysql) for additional instance info.
• [ ] 2. https://github.com/polarismesh/polaris/pull/1262.
• [ ] 3. merge instance data cache from user and instance.
• [ ] 4. auto-clean job for instances no longer exist.
• [ ] 5. add support for boltdb data storage.