ServiceX init CLI Command

[MattShirley]

Description

1. New CLI Command servicex init
2. Command line options for atlas and cms
3. Also --url for custom url
4. If no options are provided switch to little wizard that offers "A for ATLAS or C for CMS"
5. User will be prompted with a URL to create profile and get a token
6. User pastes token and cli create .servicex file in current working directory
7. User will be prompted for a download directory with a default of ./download
8. Print a success message (after an authenticated ping message sent to server)

Notes

1. Remove the download .servicex button
2. Make the "Copy Token" button bigger and have the text