Display winners of bounties within a hack

**User Story:**
As a funder
I want to highlight the winners of the different bounties within my hackathon
So that people can easily see the winning submissions

**Acceptance Criteria**

**Create new Winners tab**
GIVEN I have created a hackathon
AND it is past the end date of that hackathon
WHEN I navigate to the prize explorer for that hackathon
THEN there will be a new tab labeled "winners"
AND this will be the default landing page when going to the prize explorer
AND this should only display when the hackathon is past its end date

**Viewing Winners Tab**
GIVEN i have a hackathon that is compelted/past its end date
WHEN i view the new "Winners" tab on the prize explorer
THEN i should see all projects that meet 1 of the following criteria from any bounty in the hackathon:
- Marked as winner
- Successful tx for a payout
AND only display the project once if it meets both criteria

**Navigating to Winners Tab via gitcoin.co/hackathons: “Completed” tab**
GIVEN i am viewing gitcoin.co/hackathons
AND i am on the completed tab
WHEN i click the call to action (renamed to View Winners)
OR i click the title of the hackathon
THEN i will be navigated to the new "Winners" tab of the prize explorer for that hackathon

**Navigating to Winners tab via Hackathon onboarding page**
GIVEN i am viewing the onboarding page for a hackathon
AND that hackathon has ended
WHEN i click the call to action button (renamed from Join Now --> View Winners when hack is over)
THEN i will be navigated to the new "Winners" tab of the prize explorer for that hackathon

**Product & Design Links:**
https://www.figma.com/file/8AFLrc4dx9xnMXUkWOAaAR/Existing-Bounties-Updates?node-id=586%3A1117

Start by tracing the prize explorer, the completed tab at gitcoin.co/hackathons, and the hackathon onboarding page, using the linked Figma design for the intended layout. Done means completed hackathons route to a Winners tab that lists each qualifying project once, while active hackathons retain the existing prize-explorer behavior.

Written by the indexing model from the issue text.