* Impl new mod `hosting` for detecting git hosting services
* Refactor: Make `guess_git_hosting_services` associated fn of `GitHostingService`
* Set default value of `PkgMeta::pkg_url` to `None`
* Impl new method `get_redirected_final_url`
* Use `get_redirected_final_url` in `GhCrateMeta::find` to make `guess_git_hosting_services` more accurate.
* Use redirected `repo` in `GhCrateMeta::launch_baseline_find_tasks`
* Refactor `<GhCrateMeta as Fetcher>::find`
* Mod `get_default_pkg_url_template` to ret `&[&str]`
* Add more default `pkg-url` templates
* Rm `pkg-url` in `bin/Cargo.toml`
Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>
