This referendum will add two more currencies to the allow list of the currencies allowance pallet:

* Stellar EURC (issues by Circle)
* axlUSDC

This enables these two currencies to be used with our Forex AMM (powered by Nabla).

Added allowed currencies that possible to use chain extension

# Arguments
* `currencies` - list of currency id allowed to use in chain extension

- Problem Statement: Introducing Stellar EURC and axlUSDC to the currencies allowance pallet for the Forex AMM.
- Significance: Enhancing the usability of the Forex AMM by including additional currencies.
- Proposed Solution: Adding Stellar EURC and axlUSDC to the currencies allowance pallet.
- Expected Outcomes: Improved functionality and diversity in the Forex AMM, benefiting users and expanding the platform's capabilities.

#42 Add new assets to allow list of tokens allowance pallet