Add some ways to work with user_email in remove_project_collaborator() and update_project_collaborator()

When using remove_project_collaborator() or update_project_collaborator() one needs user_id which is not exactly easy to get. It can be extracted from list_project_collaborators() which provides the info, but it is not really handy or intuitive.

Either remove_project_collaborator() and update_project_collaborator() should take also user_email besides user_id to allow editing collaborators for project. Or there could be new Endpoint and client function to get user_id from user_email.

首先阅读 remove_project_collaborator()、update_project_collaborator() 和 list_project_collaborators()，了解它们当前如何处理 user_id。明确预期结果是在现有函数中支持 email，还是提供一个 user_id 查询端点，然后定义 API 行为以及证明使用所选方案可以正常更新协作者所需的测试。