competition reward functionality added

@ mention of reviewers`

@Didayolo`

A brief description of the purpose of the changes contained in this PR.

Now users can add reward text to the competition either through the editor or yaml file

What is done in this PR

• Add/Update reward text
• Add reward in competition creation and updation
• Add reward in yaml
• update v2 unpacker to unpack reward
• Show reward in competition list card

Screenshots

When reward is not added

When reward is added

Competition list shows reward icon when competition has reward

Issues this PR resolves

• #764 (closed) -> Editor / YAML fields -> Point 3

Checklist

• Code review by me
• Hand tested by me
• I'm proud of my work
• Code review by reviewer
• Hand tested by reviewer
• CircleCi tests are passing
• Ready to merge