🦺[Tech Debt]: Keep sync running in the background

[kcw-grunt]

Describe the work to be done

Situation

The sync process has always pauses when the user puts Litewallet in the background.

Optimization

We want to improve the process for users to have a better experience. They should be able to complete sync while doing other activities and the device is on.

Steps to complete

• Check the mechanisms that start and stop the sync process
• Review public synchronized void startSyncingProgressThread(Context app)
• Review `public synchronized void stopSyncingProgressThread(Context app) '
• Test foreground and background sync process
• Recommend Test suite