Add CLI interface for non-interactive

[MewX]

Using bazel + gazelle builds.

Going to support non-interactive cli mode only.

CLI module:

• https://github.com/spf13/cobra
• https://github.com/urfave/cli (preferred)

Should provide place holder arguments:

• [x] login #3
• [x] info/config: n_thread, user_agent, cache_size, max_parallel, max_download_file (need to copy codes from BaidupanPCS-Go, savedir #12
• [x] download one movie and all episodes - with save folder/file name #8 #9 #10 #11
• [ ] search, result paging #7
• [x] register #5
• [x] anonymous mode (web API: using wechat watch code) #6
• [x] set proxy (http/https/auto/socks5)
• [x] override cookies
• [ ] exit

[MewX]

Each placeholder should be tracked in separate issues

[MewX]

Used an old version of https://github.com/urfave/cli because newer version used go.mod which was poorly supported by gazelle.