Updated Brave (Muon) import: you can now import Brave Payments, Windows and Tabs, and data related to the referral program

[bsclifton]

Description

Users could already import from the older Brave (Muon; aka browser-laptop). With the 0.57.x milestone, we have added support for the following:

• Importing Brave Payments data (wallet, publisher settings) Import relevant settings from Brave Payments #2050, Implement wallet import/migration for existing users. Follow up to #24 #1215
• If Brave Payments data is imported, any pinned sites will become recurring tips Muon Upgrade: Pinning to Recurring Tips workflow #1910
• Importing windows and tabs Support importing tabs from legacy Brave (Muon) #998
• Importing referral program data (if it exists) Import additional data related to referral promo and retention tracking for continuity with Muon #1884

[bsclifton]

During the dev cycle, there were some complications. Some of the related issues (bugs, regressions, etc). Here's a few examples (full list visible in 0.57.x milestone)

Brave Payments

• Import not working (handlers firing out of order) Importing Brave Payments from Brave (old) is not working #2312
• Import hangs if you have a wallet but Brave Payments is disabled Import stalls if Payments data if data exists in muon but Payments is turned off #2337
• "no tokens yet" after importing a wallet which has a balance "Sadly, no tokens yet" after importing wallet with non-zero balance #2260
• Summary not shown on rewards page Summary is not shown in settings page #2350
• Data was importing but not showing properly in the UI Values in brave://rewards are using defaults, not values from publisher_state #2265

Referral program

• all data except promo code was imported promo code is not imported from browser laptop #2344

Windows / Tabs

• Loading more than a few tabs would have performance issues beachball/perf hit after importing many tabs from muon #2374
• Internal URLs (about:brave, about:preferences) that get imported don't resolve Internal URLs imported from Muon fail to resolve #2361

Pinned tabs

• favicons not show for tips imported pinned sites do not display favicons when they become Tips #2355
• clicking Learn more didn't work clicking "Learn More" on the "Tips have changed" notification doesn't display the modal #2364