Panel slow to load balance

[srirambv]

Description:

Wallet panel can be slow to load balance. We should utilize balance cache added in https://github.com/brave/brave-browser/issues/35986 to load the balance for the selected Dapp account(s) & networks to display the native token balance quickly to avoid long delays when panel is opened (currently more noticeable on panel with wallets utilizing many networks and/or accounts with balance).

Steps to Reproduce

1. Restore wallet that has balance in Eth testnet
2. Connect wallet to a Dapp
3. Open panel, shows balance as 0
4. Open wallet and select the token from testnet, shows actual balance

Actual result:

https://github.com/brave/brave-ios/assets/17010094/1cdabdfc-cae4-41bb-93bf-f128dc6980b4

Expected result:

Show balance on panel

Reproduces how often: [Easily reproduced, Intermittent Issue]

Easy

Brave Version:

• Can you reproduce this issue with the most recent build from TestFlight? Yes
• Can you reproduce this issue with the previous version of the current build from TestFlight? Not checked
• Can you reproduce this issue with the current build from AppStore? Not checked

Device details:

iPhone 13 (iOS 17.4)

Website problems only:

• did you check with Brave Shields down? NA
• did you check in Safari/Firefox (WkWebView-based browsers)? NA

Additional Information

cc: @nuo-xu @StephenHeaps

[StephenHeaps]

Seems like balance fetch is slow here (last frame of video shows balance on the panel). We'll look to see if we can improve this before balance caching lands.