Suggest moving some common utilities to an individual repository

## Feature Request

**Is your feature request related to a problem? Please describe:**

**Describe the feature you'd like:**

TiDB has many common utilities e.g., gctuner, cgroup, which can be shared by other go projects like PD. It will be good to move them to an individual repository to avoid implementing them multiple times in different projects. The same things happen on PD also.

**Describe alternatives you've considered:**

**Teachability, Documentation, Adoption, Migration Strategy:**