Support black-whist list

[3pointer]

Feature Request

Describe your feature request related problem:

Currently, BR only support three modes of backup:

• Full backup
• One DB backup
• One Table backup And we may need support more general way of backup like black-white list on DBs or Tables,

  Describe the feature you'd like:

  1. Add config about black-white list, like DM black-white list
  2. use simple wildcard in command.
  3. other ideas

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

[kennytm]

Just a note, the black-white-list function is already implemented in the BR library.

https://github.com/pingcap/br/blob/e462f80577a2bf8b5adebab2c20cc26a17db19f8/pkg/task/common.go#L90

the question is how do we expose this feature in the CLI. So this is mostly a bikeshed color question 🙃.