Clean up earn page

[0xean]

• remove By Provider page and the toggle
• Show only "By Asset" as default view
• Thorchain savers only show up for users with existing positions in the specific saver
• Add "View Only" tag to existing savers positions with tooltip directing users to thorchain for more info on the savers deprecation

[gomesalexandre]

@0xean don't think this is a blocker for this but found a bug while implementing this:

#8875

Ideally should be tackled alongside it, but as with all things DeFi section, you never know if it'll take an hour or 10, will time-cap it as a stretch of this issue for things not to look broken