IndexedDB: implement LqtVotingNotes IDB table

[TalDerei]

LqtVotingNotes:

• We want to track which notes can be voted with for the current LQT
• We have two levers:
  • Querying the nullifier set for the LQT at the current epoch for each of our notes
  • Indexing delegation notes by epoch and filtering for all those notes that originate in epoch - 1
  • The table must update when:
    • We vote
    • We spend the delegation note (e.g, to roll it over)

[TalDerei]

note for prosperity; I think the table may be extraneous. we already have an existing IndexedDB storage method getNotesForVoting which iterates over the SNR set and retrieves eligible delegation notes. We should instead have a facility in the block processor that detects LQT voting notes and saves them in a dedicated table.