feat(common): add blork assertions for git methods

[antongolub]

export const gitConfigAdd = <T extends IGitConfigAdd>({
  cwd,
  key,
  value,
  sync,
}: T): TGitResult<T> => {
  check(cwd, 'cwd: absolute')         // ← Here
  check(name, 'name: string+')        // ← 

  return gitExec({
    cwd,
    sync,
    args: ['config', '--add', key, value],
  }) as TGitResult<T>
}