Feature/ssv deposit balance

[ccali11]

@shanejearley - Please see PR for #24. Worth reviewing a bit together to discuss a few findings as well as unresolved notes that I have. Here is a checklist we can review:

• Resolve terminal error: Error: Transaction reverted: function selector was not recognized and there's no fallback function
  • Submit a bug report and tag Shane
• Potentially better handle promise returned from await ssv.connect(provider).getUserBalanceForPool(userAddress, pool) (including current for loop implementation in front-end component)
• Review with Chris where would be best to declare the refs we want exposed on front-end (inside the composable function or outside)
• Discuss time delay required to submit multiple transactions
• I noticed a new directory that got added to my branch at some point (perhaps during a Live Share). Perhaps you know where it came from and can tell me if I should include it in this PR: services/auth/
• Typing errors
• Add Ledger and WalletConnect

Looking forward to catching up!

[shanejearley]

@ccali11 the last two commits add ethers.Signer implementations for Ledger and WalletConnect in the common directory. Can you pull the latest down and test the WalletConnect message signer method in your UI (I don't have WalletConnect set up)?

Let's meet on this since I probably need to explain myself (went a bit overboard, but this should standardize things well moving forward).

[shanejearley]

Approved and suitable to merge once we confirm all ethers wallets are working as expected for check balance, deposit, and sign message.