Proposal: Support better query for pools

[mattverse]

Background

We currently only have a single query for querying all Pools, namely osmosis/gamm/v1beta1/pools. But with different pools existing under different circumstances, and with over 500+ pools existing in state as of right now, there are situations where a person would like to query pools with a certain filter, or a whitelist.

I would like to propose two different ways of supporting better queries for pools.

Suggested Design

1. The first way of doing this can be done via creating a pool query that accepts different filter as its request, something like this

message QueryPoolWithFilterRequest {
       int64 minLiquidity = 1;
       string poolType = 2;
      int64 minPoolAssetNum = 3;
      ...
}

and then whoever's requesting can use the field that they want to use as a filter, leaving other fields with null value. The response would be returned via iterating over pool state, only returning the pools that goes under the filtered request.

2. The second way of doing this is a quite untraditional way of supporting queries, which is done via using app.toml. We create a field in app.toml where the node operator can have their own list of whitelist pool ids. Then we have a query, say QueryPoolsUnsafe, which would non-deterministically only return the state of the pools that are whitelisted in app.toml. Using the QueryPoolsUnsafe query, who ever's querying does not have to go through the process of having to query all states of pools first, and the filtering them within the client side.

Open for discussions on the pros and cons of these ways, and also if we even do need these queries!