Add multi-currency support for Flow pallet

[vovacha]

User Story

As a user, I want to create a campaign using different currencies so I can spend those tokens later using governance mechanisms.

Acceptance Criteria

1. Create a campaign with multiple currencies.
2. Contribute to a campaign with multiple currencies.
3. only stablecoins can be used to fund into campaigns

Additional Information

• probably a list of tokens should be defined which contains lists allowed for payments. (today aUSD & PLAY)

How to test

TBD

1. a
2. b
3. c
4. d

[vovacha]

Moved: playzero/zero-network#186