Add command to download all submissions of a challenge

[Ram81]

Description

We need a cli command that will allow users to download all submissions of a challenge. The command should handle two cases:

1. If a user is host of a challenge download all submissions made to the challenge for a phase
2. If a user is a participant download submissions only made by the team of user to the challenge for a phase.

Required backend APIs are already available for this feature here.

[burnerlee]

@Ram81 may I pick up this issue and make a quick PR?

[Ram81]

@burnerlee sure, go ahead

[burnerlee]

@Ram81 in what file format should the submissions be downloaded?

[burnerlee]

@Ram81 ping

[burnerlee]

@Ram81 ping

[Ram81]

@burnerlee we should give two options csv and json. Sorry about the late reply

[burnerlee]

Not a problem at all😅 I'll make a PR to integrate this😀 thanks

[burnerlee]

@Ram81 also where do I save the files download by the user? I am planning to make a new folder at project root level named submissions. When the user runs the command through the cli to download submissions. by default the submissions would be downloaded in csv format and stored in the submissions folder with a name of format submissions_<time_string_at_command_run> . To download a json file the user can use the --json flag.

[burnerlee]

Please suggest changes in this approach if needed

[burnerlee]

@Ram81 ping