feat: Add manual sync accounts

[obany]

Description of change

Adds the ability to manual sync accounts with refresh on transactions panel.
The sync at login is also now done as a background task, which reduces the time it shows the busy screen for when logging in. This was very slow on large accounts (or stopped if no internet connection), making it look like the app had crashed, instead the manual sync indicator is active on login.
The settings->resync is also wired in to the same processing (possible we could remove this now that you can sync from the main UI)

Fixes

#351 #331

Type of change

• Bug fix (a non-breaking change which fixes an issue)
• Enhancement (a non-breaking change which adds functionality)

How the change has been tested

Test on windows, mac and ubuntu

Change checklist

Add an x to the boxes that are relevant to your changes, and delete any items that are not.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes