[Namadillo]: popup tx to user to consolidate MASP notes

[brentstone]

Namadillo should ask the user to sign a tx every so often that can consolidate their MASP notes, such that the number of notes is kept as low as possible.

[neocybereth]

What it is: Shielded transfer to yourself

Issue:

• We always unshield to pay fees
• Too many notes so txn's can be too big for Ledger
• Spending so many notes makes calculating proof take long
• We retrieve high notes => small notes so 90% is easy to unshield but last 10% could be a pain

Solutions:

• Potentially batch a consolidation transaction for every shielded action
• Add some consolidation UI and pick a number of transactions to consolidate.