Add `repo` subcommand to interact with Repo entities

[noahingh]

Is your feature request related to a problem? Please describe.
I want to access Repo entities by CLI command. It should provide list, get, and update utilities for Repo.

Describe the solution you'd like
Add RepoService type to the api package to interact with a server.

func main() {
  ...

  client := NewClient(...)
  repo, err := client.Repos.GetRepo(ctx, "gitploy-io", "gitploy")

  ...
}