[$60] Apply skills set to challenges created

[jmgasper]

When creating a challenge for a Git issue, we need to make sure the skills set on the project are applied to the challenge. The new skills come from: #478

To set the skills, after the challenge has been created:

POST to https://api.topcoder-dev.com/v5/standardized-skills/work-skills

BODY:

{
    "workId": <Challenge ID>,
    "workTypeId": "413340e8-f56f-4061-8796-c916dfa82770",
    "skillIds": [
        <GUID IDs of the v5 skills to apply>
    ]
}

The work type ID can be configurable, but will not change dynamically - it's fine to make this an env variable.