Add additional bounty owners

**User Story:**
As a funder
I want to be able to add multiple bounty owners
So that the payout isn't constrained to just myself

**Acceptance Criteria**

**Form/field Initiation**
GIVEN i am creating a bounty
WHEN I navigate to the payout step of the new wizard
THEN there will be a field to add bounty owners
AND this field should be a type ahead, searching on Gitcoin profile names
AND by default I, original bounty creator should be added there by default
AND i should be able to add multiple people as bounty owners outside of my self

**Adding additional bounty owners**
GIVEN i am creating a bounty
AND i am on the payout step of the new wizard
WHEN i search for a profile in the Bounty Owner type ahead
AND click the desired name
THEN the dropdown should close and I should see that username next to mine in the bounty owner field
AND anyone who is listed in that field should have access to pay any contributor out using their own wallet
AND each name should have an 'x' to remove the as a bounty owner EXCEPT my self, the original bounty creator

**Removing a name as a bounty owner, prior to submission**
GIVEN i am creating a bounty
AND i am on the payout step of the new wizard
WHEN i click the 'x' on someones name in the Bounty Owner field
THEN that name should be removed from the list of bounty owners
AND that profile should not have access to pay out bounty submissions

**Product & Design Links:**
https://www.figma.com/file/8AFLrc4dx9xnMXUkWOAaAR/Existing-Bounties-Updates?node-id=33%3A1854

Start by reviewing the payout step of the new bounty wizard and the linked Figma design. Trace how bounty owners and contributor payouts are currently represented, then define the changes needed for searchable profile selection, owner removal, and wallet-based payout access. Done means the acceptance criteria are met and the relevant payout flows are covered by tests.

Written by the indexing model from the issue text.