Support for push command for predictions category

**Is your feature request related to a problem? Please describe.**
Include support for `amplify push` command for prediction category.

**Describe the solution you'd like**
It would be much better to have a command like `amplify push predictions [resource name]`. Seems like, the only way to deploy predictions category is running `amplify push` but it'll deploy other categories as well. I would like to deploy AppSync and DynamoDB after determining the GraphQL schema that's why I don't wanna use `amplify push` without category as much as possible.

**Describe alternatives you've considered**
So far I'm using predictions resources by creating via Console, and then use it as existing resources but it would be much efficient with `amplify push predictions` command.