Fix UI initialization flow and reset when devices < 2 from native side

[darkdh]

fix brave/brave-browser#2533
fix brave/brave-browser#2537
fix brave/brave-browser#2540
fix brave/brave-browser#2552
fix brave/brave-browser#2575

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
  • Windows
  • macOS
  • Linux
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone

Test Plan:

Except test case in above issues, here is the critical case:

1. Create sync chain on device a
2. Connect to sync chain on device b
3. Remember the sync code of the sync chain
4. Delete device b on device a
5. Both device should be reset to unsync state after a while
6. Create sync chain on device a, the sync code should be different than step 3
7. Create sync chain on device b, the sync code should be different than step 3

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

[AlexeyBarabash]

++

[cezaraugusto]

tested and confirmed it fixes all referenced issues but not brave/brave-browser#2523 which is fixed already, and brave/brave-browser#2527 which was not fixed while trying these changes. otherwise lgtm great work on this one

[darkdh]

master: 7b1ff67
0.60.x: 5d8dfaa
0.59.x: 80eda77
0.58.x: 7524ffc

[kjozwiak]

Changing the flag as this has already been merged into 0.58.x:

0.58.x: 7524ffc

After talking with @rebron, we'll keep this in 0.58.x even though it was merged without approval. Sync is going to be disabled by default in 0.58.x so this won't risk breaking regular users who haven't enabled sync. Please wait for approval next time before merging.

[kjozwiak]

Also moved the following into 0.58.x as they've been resolved by this PR as mentioned above:

• re-enabling wifi does not show sync QR code or words brave-browser#2537, QR code/words don't display if you try to join a sync chain before starting a new one brave-browser#2540, Sync chain not being reset when Main device is removed brave-browser#2575