AIP - 85: Rebrand agEUR into EURA

## Proposal This is a vote to change the symbol and name for the agEUR contract wherever it is deployed so it becomes EURA rather than agEUR. And also to change stEUR name for `staked EURA`. stEUR is to keep its current symbol, just like agEUR (EURA) logo should remain the same. You can read more on the added value of rebranding in the discussion forum. ## Implementation This requires upgrading the protocol agEUR and stEUR contracts on all chains on which it is deployed and setting the new...