Add --info, --switch, --create, --scan command

[small-tou]

-i, --info     Show current git user
-s, --switch   Switch git user
-c, --create   Create a new git user
-S, --scan     Scan all git repo in current directory, and show the git user of each repo

[geongeorge]

Thanks @0xYootou for the PR. I feel like dropping the default git switch ui will be bad experience for the existing users

[small-tou]

@geongeorge ok, i will modify the code.

[small-tou]

@geongeorge i have reset main function code. Please look at the code again, thank you.