Feat/unigivpower sem review

[aminlatifi]

Applied changes to address @sembrestels feedback. https://github.com/Giveth/givpower/pull/32#issuecomment-1627700006

Also added DepositTokenDeposited and DepositTokenWithdrawn events to facilitate deposit token balance monitoring, particularly on Subgraph

[divine-comedian]

Once this is done we need to:

• deploy contracts to Optimism Goerli
• update the optimism goerli giveconomy subgraph