Feature: Allow defining targets per pattern or group

[jmullo]

Prerequisites

• [X] I have written a descriptive issue title
• [X] I have searched existing issues to ensure the feature has not already been requested

🚀 Feature Proposal

It would be very useful to be able to define target levels per pattern or group.

Not matching ones would use default target.

Motivation

For certain dependencies we know that it's safe to automerge majors and for some other dependencies it's not.

Example

target: minor
custom-targets:
  - target: major
    patterns:
      - "@foo*"
    groups:
      - "dev-dependencies"