Detect & fallback for pathfinding payments > 88 TLs (let's be on the safe side and do 80?)

[WietseWind]

Detect & fallback for pathfinding payments > 88 TLs (let's be on the safe side and do 80?)

https://monkdesk.xrpl-labs.com/agent/ticket/73027

1. show message
2. change payload to one-asset (so the user can convert first and then pay anyway as a fallback)