add `config` command

[sujaykumarh]

add `config` command

[sujaykumarh]

example config

{
  "global": {
    "default_profile": "personal",
    "command": {
      "git": {
        "init.defaultbranch": "main",
        "gpg.program": "/usr/bin/gpg",
        "pull.rebase": "false",
        "pull.ff": "only",
        "commit.gpgsign": "true",
        "core.editor": "nano",
        "user": {
          "name": "Jon Doe",
          "email": "[email protected]"
        },
        "signingkey": "XXXXXXXXXXXMy"
      }
    }
  },
  "profile": {
    "work": {
      "path": "/path/to/work/dir",
      "command": {
        "git": {
          "user": {
            "name": "Jonny Doe",
            "email": "[email protected]"
          },
          "commit.gpgsign": "true",
          "signingkey": "XXXXXXXXXXXWork"
        }
      }
    },
    "personal": {
    }
  }
}