feat: add download votes button

[Sekhmet]

Summary

This PR adds functionality to download votes for s spaces.

UI is temporary as it wasn't specified in the issue, but functionality should be good.

Currently server returns bad response while report is generated (doesn't return PENDING_GENERATION).
This PR contains workaround to handle that response:

{
    "jsonrpc": "2.0",
    "result": "0",
    "id": "0x345d62b550421b53c717ca2ca9b3edd4ebe6a4c12cef0ed26493d5164c22c4c6"
}

Closes: https://github.com/snapshot-labs/workflow/issues/336

How to test

1. Go to offchain (s) space.
2. Go to proposal that has passed.
3. Try downloading it.
4. You will get notification if it's still pending or it will prompt you to download report if it's ready.

Screenshots

Current UI:

[bonustrack]

tACK