SPIKE: Prevent iPhone connection from going to sleep

[JonRay15]

Chore

This is one of three remaining issues to be solved in order for the mobile wallet extension to be viable in the long term

Acceptance criteria

• [ ] The wallet connection does not frequently go to sleep

Notes

Other issues to resolve:

• https://github.com/vegaprotocol/vegawallet-browser/issues/760
• https://github.com/vegaprotocol/vegawallet-browser/issues/795

[JonRay15]

This is not possible ..... closing.