Proposal history

[fmorency]

Proposals are regularly pruned from the chain to avoid chain bloat. The pruning makes it impossible to properly track the complete history of a given proposal from the chain.

However, the YACI indexer contains the full chain history. We could leverage the full history to index proposals at every lifecycle step. The index could also enhance proposal filtering capabilities, i.e., only list proposals matching a predicate.

Create a page leveraging the YACI proposal indexing capabilities to enable proposal history display.

Relates liftedinit/yaci#44