[cspp] Integrate cspp into decrediton

[vctt94]

This is a list of what is needed so far for finishing the cspp integration with decrediton.

• [x] Add Privacy Page - only allow to see if changed in settings
• [ ] Add Privacy tutorial for beginners
• [x] Add method to create necessary initial accounts
• [x] Add indicator mixer is running
• [ ] Flag wallet as mixed, which will have different behaviors such as:
  • [x] Prevent receiving funds on mixing account
  • [x] Prevent spending from unmixed account
• [ ] Allow to restore private wallet
• [ ] Lock wallet when mixing is done
• [ ] Warn when trying to close wallet and mixer is running

This was discussed at matrix but still open for debate, if someone has a different opinion, please let us know.

[matheusd]

Some ideas, in no particular order.

• [ ] Flag mix transactions as such (ideally this would be done by dcrwallet itself since it knows which transactions were done in conjunction with the cspp server but we can use some heuristics to do that ourselves)
• [ ] Improve txdetails ui for mix transactions (too many addresses clutter the ui, there are some visual issues in the page when showing mix transactions)
• [ ] Have some CSPP-specific stats/logs (how many mixes we participated in, existing utxos)

[xaur]

• Prevent receiving funds on mixing account
• Prevent spending from unmixed account

It would be nice to have these protections in dcrwallet and reused from there to avoid duplication.